ARM: 6286/1: fix Thumb-2 decompressor broken by "Auto calculate ZRELADDR"

"ARM: Auto calculate ZRELADDR and provide option for exceptions" broke
the Thumb-2 decompressor because it removed an entry in the LC0 table
but didn't adjust the offset the Thumb-2 code uses to load the SP from
that table.

Fix it, and also change the ARM code to use the separate SP-load since
ARM instructions that include the SP in the LDM register list are
deprecated.

Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>