x86/boot/e820: Rename gap_start/gap_size to max_gap_start/max_gap_start in e820_searc...

x86/boot/e820: Rename gap_start/gap_size to max_gap_start/max_gap_start in e820_search_gap() et al

The PCI gap searching functions pass around pointers to the
gap_start/gap_size variables, which refer to the maximum
size gap found so far.

Rename the variables to say so, and disambiguate their namespace
from 'current gap' variables.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H . Peter Anvin <hpa@zytor.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20250515120549.2820541-23-mingo@kernel.org