Remove floating point formatting in newlib nano

[c1728p9]

Remove special case targets which have floating point enabled in
Newlib Nano from gcc.py. To enable floating point printf/scanf
for a target configure it to use the 'standard' default build in
targets.json rather than 'small'.

[c1728p9]

@mbed-bot: TEST

HOST_OSES=ALL
BUILD_TOOLCHAINS=ALL
TARGETS=ALL

[mbed-bot]

[Build 623]
FAILURE: Something went wrong when building and testing.

[0xc0170]

Test results: OK

A question : this would be non breaking if all targets in the list there are built with newlib (not small nano). Are they? Looking at them, NUCLEO_F410RB is with small. We know that there are some issues with nucleo targets for uARM (there's one PR open that can help us with this, it needs review). I'll have a look and get back to this. Or another option, as this is for gcc -> it's used offline only, we could display a logging warning that this has changed, and floating stdout/in is not enabled now (if target is in the list + standard lib == small -> display warning).

[0xc0170]

Depends on https://github.com/mbedmicro/mbed/pull/2098/files. That one fixes all targets we care in this list removal, I checked, all of them would be then standard lib -> non-breaking change

[0xc0170]

2098 was merged, this should be good to go

@screamerbg please review

[screamerbg]

LGTM. Mind if I ask Renesas team to confirm? They had some concerns

[bridadan]

/morph test

[mbed-bot]

Result: FAILURE

Your command has finished executing! Here's what you wrote!

/morph test

Output

mbed Build Number: 508

Test failed!

[0xc0170]

@TomoYamanaka Are you happy with this change?

[TomoYamanaka]

Thank you for your information.
Renesas team is now reviewing about this changing.

[TomoYamanaka]

In this floating point formatting problems,
if the main cause is that using the "newlib-nano", there is no problem with this change.