This reverts commit 3f6884902b.
This commit does not work as intended: the part in arch/arm/Makefile
gets ignored and -mcpu=cortex-m3/4 does not get passed to gcc. It seems
that the zephyr toolchain does not care, but the vxworks assembler
chokes if it is missing, and thinks the CPU does not support thumb ISA
Change-Id: I14d11d3e22dac4952bdab3eb9e2d1c36b1a686c2
Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>