pcmcia: update gfp/slab.h includes

Implicit slab.h inclusion via percpu.h is about to go away.  Make sure
gfp.h or slab.h is included as necessary.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
diff --git a/drivers/pcmcia/pcmcia_cis.c b/drivers/pcmcia/pcmcia_cis.c
index 7406387..4a65eaf 100644
--- a/drivers/pcmcia/pcmcia_cis.c
+++ b/drivers/pcmcia/pcmcia_cis.c
@@ -14,6 +14,7 @@
  *
  */
 
+#include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/netdevice.h>