pcmcia: Removed unused variable control.

Kernel test robot throws below warning ->
drivers/pcmcia/omap_cf.c:127:7: warning: variable 'control'
set but not used [-Wunused-but-set-variable]

Removed unused variable control.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Souptick Joarder (HPE) <jrdr.linux@gmail.com>
[linux@dominikbrodowski.net: retain omap_readw() call, as it might be required]
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>