parisc/unaligned: Fix fldd and fstd unaligned handlers on 32-bit kernel

Usually the kernel provides fixup routines to emulate the fldd and fstd
floating-point instructions if they load or store 8-byte from/to a not
natuarally aligned memory location.

On a 32-bit kernel I noticed that those unaligned handlers didn't worked and
instead the application got a SEGV.
While checking the code I found two problems:

First, the OPCODE_FLDD_L and OPCODE_FSTD_L cases were ifdef'ed out by the
CONFIG_PA20 option, and as such those weren't built on a pure 32-bit kernel.
This is now fixed by moving the CONFIG_PA20 #ifdef to prevent the compilation
of OPCODE_LDD_L and OPCODE_FSTD_L only, and handling the fldd and fstd
instructions.

The second problem are two bugs in the 32-bit inline assembly code, where the
wrong registers where used. The calculation of the natural alignment used %2
(vall) instead of %3 (ior), and the first word was stored back to address %1
(valh) instead of %3 (ior).

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org