x86/boot/e820: Create coherent API function names for E820 range operations

We have these three related functions:

 extern void e820_add_region(u64 start, u64 size, int type);
 extern u64  e820_update_range(u64 start, u64 size, unsigned old_type, unsigned new_type);
 extern u64  e820_remove_range(u64 start, u64 size, unsigned old_type, int checktype);

But it's not clear from the naming that they are 3 operations based around the
same 'memory range' concept. Rename them to better signal this, and move
the prototypes next to each other:

 extern void e820__range_add   (u64 start, u64 size, int type);
 extern u64  e820__range_update(u64 start, u64 size, unsigned old_type, unsigned new_type);
 extern u64  e820__range_remove(u64 start, u64 size, unsigned old_type, int checktype);

Note that this improved organization of the functions shows another problem that was easy
to miss before: sometimes the E820 entry type is 'int', sometimes 'unsigned int' - but this
will be fixed in a separate patch.

No change in functionality.

Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Jackson <pj@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>