This is a follow-on to commit 62e88b1c 'mm: Make
arch_unmap()/bprm_mm_init() available to all architectures'

I removed the asm-generic version of arch_unmap() in that patch,
but missed arch_bprm_mm_init().  So this broke the build for
architectures using asm-generic/mmu_context.h who actually have
an MMU.

Fixes: 62e88b1c 'mm: Make arch_unmap()/bprm_mm_init() available to all architectures'
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20141122163711.0F037EE6@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>