parisc/unaligned: Fix emulate_ldw() breakage

The commit e8aa7b17 broke the 32-bit load-word unalignment exception
handler because it calculated the wrong amount of bits by which the value
should be shifted. This patch fixes it.

Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: e8aa7b17 ("parisc/unaligned: Rewrite inline assembly of emulate_ldw()")
Cc: stable@vger.kernel.org   # v5.18