sparc: fix compat recv/recvfrom syscalls

sparc has the wrong compat version of recv() and recvfrom() for both the
direct syscalls and socketcall().

The direct syscalls just need to use the compat version. For socketcall,
the same thing could be done, but it seems better to completely remove
the custom assembler code for it and just use the same implementation that
everyone else has.

Fixes: 1dacc76d ("net/compat/wext: send different messages to compat tasks")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>