arm: use generic fixmap.h

ARM is different from other architectures in that fixmap pages are indexed
with a positive offset from FIXADDR_START.  Other architectures index with
a negative offset from FIXADDR_TOP.  In order to use the generic fixmap.h
definitions, this patch redefines FIXADDR_TOP to be inclusive of the
useable range.  That is, FIXADDR_TOP is the virtual address of the topmost
fixed page.  The newly defined FIXADDR_END is the first virtual address
past the fixed mappings.

Change-Id: If76f8fd5b9e7e244155eecd76bd9cae40b3b15f0
Signed-off-by: Mark Salter <msalter@redhat.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Git-commit: 1ff4afb4bb09f43a5da75c854af82198eb4aacb5
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git


Signed-off-by: Venkatesh Yadav Abbarapu <vabbar@codeaurora.org>