mips: SoC or board specific override of flush_dcache_range()

[Alex Nemirovsky]

Hello Daniel et. all,

We have a need to override what is done inside 
arch/mips/lib/cache.c::flush_dcache_range()
for our SoC/board.

Easiest approach seems to be making the function __weak upstream.  i.e.

-void flush_dcache_range(ulong start_addr, ulong stop)
+void __weak flush_dcache_range(ulong start_addr, ulong stop)

thoughts?

Thanks
-AN