x86/boot/e820: Remove e820__range_remove()'s unused return parameter

x86/boot/e820: Remove e820__range_remove()'s unused return parameter

None of the usage sites make use of the 'real_removed_size'
return parameter of e820__range_remove(), and it's hard
to contemplate much constructive use: E820 maps can have
holes, and removing a fixed range may result in removal
of any number of bytes from 0 to the requested size.

So remove this pointless calculation. This simplifies
the function a bit:

   text       data        bss        dec        hex    filename
   7645      44072          0      51717       ca05    e820.o.before
   7597      44072          0      51669       c9d5    e820.o.after

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/20250515120549.2820541-27-mingo@kernel.org