MIPS: MIPSsim: Remove unused code

The function prom_init_cmdline() doesn't do anything, and nobody calls the
prom_getcmdline() function. Since these two are the only functions in the
file arch/mips/mipssim/sim_cmdline.c, the whole file can be removed now
along with the call to the no-op prom_init_cmdline() routine.

Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@movial.com>
Patchwork: http://patchwork.linux-mips.org/patch/465/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>