Fix WIFI_CONNECT_PARAMS_CHANNEL_FAIL testcase.

[SeppoTakalo]

Description

Test case was assuming that secure and unsecure SSID were on different
channels.
This is not a requirement and it should be OK to run on same channel.

Fixed the testcase by using +1 on channel number to get a wrong channel.

Fixes #8227

Pull request type

[x] Fix
[ ] Refactor
[ ] Target update
[ ] Functionality change
[ ] Breaking change

[SeppoTakalo]

@VeijoPesonen Please review.

[SeppoTakalo]

@0xc0170 Reviewed by Veijo.
Please remove the "Needs: review" label and add "Needs: CI" and then start the test.

Thanks.

[0xc0170]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 3167
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/8241/

Triggering tests

/morph test
/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 2768
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8241/

[mbed-ci]

Test : FAILURE

Build number : 2975
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/8241/2975

[VeijoPesonen]

7:18:11 mbedgt: exporting to JUNIT file '/home/jenkins/k64f_test/workspace/test_matrix_raas/raas_matrix_job/target/LPC546XX/toolchain/GCC_ARM/test_report_LPC546XX-GCC_ARM.xml'...
17:18:11 mbedgt: exporting to HTML file '/home/jenkins/k64f_test/workspace/test_matrix_raas/raas_matrix_job/target/LPC546XX/toolchain/GCC_ARM/test_report_LPC546XX-GCC_ARM.html'...
17:18:11 mbedgt: unexpected error:
17:18:11 'time_start'

@0xc0170 failure seems to occur while writing a test report. Would you please restart the test job.

[0xc0170]

Will restart the job once few jobs complete

[NirSonnenschein]

/morph build

[mbed-ci]

Build : SUCCESS

Build number : 3261
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/8241/

Triggering tests

/morph test
/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : FAILURE

Build number : 2882
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8241/

[mbed-ci]

Test : SUCCESS

Build number : 3074
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/8241/3074

[NirSonnenschein]

/morph export-build
/morph mbed2-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 2887
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/8241/