ARM: msm: Add missing ENDPROC to headsmp.S

Once the ENDPROC is in place, BSYM() in not longer necessary
to get correct pointer to msm_secondary_startup().

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: David Brown <davidb@codeaurora.org>
Cc: Daniel Walker <dwalker@fifo99.com>