Following patch reworks car_disable into C. Tested, works here. I compared

Following patch reworks car_disable into C. Tested, works here. I compared
also the GCC generated code and it looks all right. Please test on some
multicore CPU.

I added the "memory" clobber to read_cr0 / write_cr0 function as it is in Linux
Kernel. Seems that if this is missing, GCC is too smart and messes the order
of reads/writes to CR0 (not tested if really a problem here, but be safe for
future users of this function  ;)

Signed-off-by: Rudolf Marek <r.marek@assembler.cz>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5562 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1