parisc: fix personality on 32bit kernel

Process personality is stored together with other flags like UNAME26 in
an integer variable.  Overwriting this value with PER_LINUX drops all
other existing flags and as such broke tools like the uname26 tool.

Actually this was only broken on 32bit kernels, since for 32bit-ELF
binaries on 64-bit kernels the SET_PERSONALITY macro from
arch/parisc/kernel/binfmt_elf32.c is used which does not modifies the
personality value at all (which is wrong as long as we don't run HPUX
binaries or similiar).

Signed-off-by: Helge Deller <deller@gmx.de>