m68k: Remove the BKL from sys_execve

This seems like a copy-and-paste from code that no-longer needs the
BKL Just remove it.

Signed-off-by: John Kacur <jkacur@redhat.com>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <alpine.LFD.2.00.0910130011180.3658@localhost.localdomain>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>