ssbi: Fix exit mismatch in remove function

msm_ssbi_remove is referenced with __exit_p, but not declared with
__exit.  This causes a warning when the driver is not built as a
module:

drivers/ssbi/ssbi.c:341:23: warning: 'msm_ssbi_remove' defined but not used [-Wunused-function]

The remove is needed for unbinding to work, even if not compiled as a
module, so just remove it.

Signed-off-by: David Brown <davidb@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>