x86-32, mm: Remove duplicated include

Commit b40827fa ("x86-32, mm: Add an initial page table for core
bootstrapping") added an include directive which is needless and is
taken care of by a previous one.  Remove it.

Caught-by: Jaswinder Singh Rajput <jaswinderlinux@gmail.com>
Signed-off-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>