x86: Further clean up of mtrr/generic.c

Yinghai noticed that i defined BIOS_BUG_MSG but added no
usage for it. The usage is to clean up this turd in generic.c:

			printk(KERN_WARNING "WARNING: BIOS bug: VAR MTRR %d "
				"contains strange UC entry under 1M, check "
				"with your system vendor!\n", i);

Breaking printk lines in the middle looks ugly, is hard to read
and breaks 'git grep'. Use the BIOS_BUG_MSG instead.

Also complete the moving of structure definitions and variables
to the top of the file.

Reported-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>