ARM: 6623/1: Thumb-2: Fix out-of-range offset for Thumb-2 in proc-v7.S

Commit d30e45ee (ARM: pgtable: switch order of Linux vs hardware page tables)
introduced a pre-increment addressing offset which is out of range for
Thumb-2.  Thumb-2 only permits offsets <256.  So split the intruction in
two for Thumb-2.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>