Use "hash" value in rtalloc_mpath_fib() instead of RTF_ANNOUNCE flag.
Hashing method is the same as in in6_src.c. (Probably we need better one).

MFC after:	2 weeks
Stop calling imx51_ccm_foo() clock functions from imx6 code.  Instead
define a few imx_ccm_foo() functions that are implemented by the imx51 or
imx6 ccm code.  Of course, the imx6 ccm code is still more a wish than
reality, so for now its implementations just return hard-coded numbers.
Add EFI support to the installer. This requires that the kernel provide
a sysctl to determine what firmware is in use. This sysctl does not exist
yet, so the following blocks are in front of the wheels:
- I've provisionally called this "hw.platform" after the equivalent thing
  on PPC
- The logic to check the sysctl is short-circuited to always choose BIOS.
  There's a comment in the top of the file about how to turn this off.

If IA64 acquired a boot1.efifat-like thing (probably with very few
modifications), the same code could be adapted there.
make_dtb.sh is designed to be used in a kernel build environment where
MACHINE is defined to the target's value, not the host's
value. However, in Makefile.inc1, it is still defined to be the host's
value. Make the makedtb target work by expanding TARGET in the
existance test, and passing MACHINE=$TARGET in the call to make_dtb.sh