build: Relax Cortex CFLAGS

 * Always set march=armv7-a
 * Use mtune instead of mcpu. Bad code is generated on A15 otherwise.

Change-Id: I215b0fd8b6240d81840b041b1919dd89498630e7
move build: move bionic optimizations to NEON makefile

Change-Id: I69e2f41dfb5626275d1fd6de1a0a1e80dc1bc2b0
Signed-off-by: PipelinerArd <kristoferard@gmail.com>

Conflicts:
	core/combo/arch/arm/armv7-a.mk