Optimized ARM RWSEM algorithm

RWSEM implementation for ARM using atomic functions.
Heavily based on arch/sh/include/asm/rwsem.h
Added filesystem dynamic read-ahead
Thanks to Chad Gooldman
Added Fast Random generator support (frandom)
Frandom is a Linux kernel random number generator, which is 10-50
times faster than what you get from Linux' built-in /dev/urandom.
And it uses very little (/dev/frandom) or none (/dev/erandom) of
the kernel's entropy pool, so it is very useful for applications
that require a handy source for lots of random data.

Conflicts:
	drivers/char/Kconfig
	drivers/char/Makefile