armv8-m: Remove redundant constant pools (#1035)

armv8-m: Remove redundant constant pools (#1035)

Currently in Armv8-M GCC/ArmClang ports, constant pool is used to
define literals needed for `ldr` instructions. However, those
constant pools are defined with `.align 4` which increases code size.
Instead of defining the constant pool with `.align 4`, let the
compiler hanlde the constant pool and the required alignment.

Signed-off-by: Devaraj Ranganna <devaraj.ranganna@arm.com>
Co-authored-by: chinglee-iot <61685396+chinglee-iot@users.noreply.github.com>
Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>