aot_compile_op_call: stop setting calling convention explicitly

[yamt]

The current logic doesn't work for some cases.
cf. #3138

It's unclear why we are setting the calling convention explicitly here at all. In many cases, the default just seems working.

[yamt]

the ci failure looks like #2776

    (import "not wasm" "overloaded" (global i64))
    (import "not wasm" "overloaded" (global f32))
    (import "not wasm" "overloaded" (global f64))
    (import "not wasm" "overloaded" (table 0 funcref))
    (import "not wasm" "overloaded" (memory 0))
  )'
exception is ....'unknown import'
Writing WAST module to 'C:\Users\RUNNER~1\AppData\Local\Temp\tmplthf_pwl.wast'
Compiling WASM to 'C:\Users\RUNNER~1\AppData\Local\Temp\tmp2ye2ialk.wasm'
Running: ./wabt/out/gcc/Release/wat2wasm.exe --enable-thread --no-check C:\Users\RUNNER~1\AppData\Local\Temp\tmplthf_pwl.wast -o C:\Users\RUNNER~1\AppData\Local\Temp\tmp2ye2ialk.wasm
Starting interpreter for module 'C:\Users\RUNNER~1\AppData\Local\Temp\tmp2ye2ialk.wasm'
Running: ../../../product-mini/platforms/windows/build/RelWithDebInfo/iwasm.exe --module-path=C:\Users\RUNNER~1\AppData\Local\Temp --heap-size=0 -v=0 --repl C:\Users\RUNNER~1\AppData\Local\Temp\tmp2ye2ialk.wasm
Removing tempfiles
failed with a non-zero return code 1

spec tests FAILED
Error: Process completed with exit code 1