Apply correct, optimized mfpu compiler flag for ARMv7-A Cortex CPUs

###########partial cherry-pick###########
For those ARMv7-A Cortex CPUs that can handle VFPv4 floating point,
We can set "-mfpu=neon-vfpv4" instead of generic "-mfpu=neon"
to gain extra performance improvements.

References :
- GCC  : https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html
- Cortex A15 :
http://www.arm.com/products/processors/cortex-a/cortex-a15.php
- Cortex A9 :
http://www.arm.com/products/processors/cortex-a/cortex-a9.php
- Cortex A8 :
http://www.arm.com/products/processors/cortex-a/cortex-a8.php
- Cortex A7 :
http://www.arm.com/products/processors/cortex-a/cortex-a7.php
- Cortex A5 :
http://www.arm.com/products/processors/cortex-a/cortex-a5.php

Change-Id: Id8b1a251234014ecf7ffbc1ae14455ed1726e028
Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
arter97 authored on Sep 9