Bump generic_mips64 system partition size.
Bump generic_mips64 system partition size.

Fix broken mips64 build via 20% increase.

Change-Id: Ie30418c6fc7cf8810139abe53537ef8259a49a2f

xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build