parisc: Only use -mfast-indirect-calls option for 32-bit kernel builds

In spite of what the GCC manual says, the -mfast-indirect-calls has
never been supported in the 64-bit parisc compiler. Indirect calls have
always been done using function descriptors irrespective of the
-mfast-indirect-calls option.

Recently, it was noticed that a function descriptor was always requested
when the -mfast-indirect-calls option was specified. This caused
problems when the option was used in  application code and doesn't make
any sense because the whole point of the option is to avoid using a
function descriptor for indirect calls.

Fixing this broke 64-bit kernel builds.

I will fix GCC but for now we need the attached change. This results in
the same kernel code as before.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org  # v3.0+
Signed-off-by: Helge Deller <deller@gmx.de>