cmake:risv_baremetal: Remove -Wno-unused-command-line-argument flag

With Iea5694f2bfdcf669a436fe23ae965848f50ab396, we don't need to silence
the warning anymore.

Also clean up the arm-only -m-strict-align flag in clang and gcc.

Change-Id: I1955e86a45838ac5cf37594b1c13ee5d80bd388a
1 file changed