--legacyalign, --no_legacyalign are deprecated from ARMC6 compiler, in order to
remove deprecated flags all linker files (GCC and IAR as well to have uniformity)
should strictly align to 8-byte boundary
pwmout:
Used SystemCoreClock
Serial fuart:
SERIAL_5 & SERIAL_3 have same CTS pin (PA7), only function register is different (4 & 2).
pinmap_peripheral() will always return first match from the map.
Hence changed as, if SERIAL_5 is used, then pinmap_peripheral() should return SERIAL_5 (function register 2 to be set).