s390/pkey: Fix checkpatch findings in pkey header file

Fix all the complains from checkpatch for the pkey header file:

CHECK: No space is necessary after a cast
+       PKEY_TYPE_CCA_DATA   = (__u32) 1,

CHECK: Please use a blank line after function/struct/union/enum declarations
+};
+#define PKEY_GENSECK _IOWR(PKEY_IOCTL_MAGIC, 0x01, struct pkey_genseck)

Suggested-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>