uapi: fix linux/nfsd/cld.h userspace compilation errors

uapi: fix linux/nfsd/cld.h userspace compilation errors

Include <linux/types.h> and consistently use types it provides
to fix the following linux/nfsd/cld.h userspace compilation errors:

/usr/include/linux/nfsd/cld.h:40:2: error: unknown type name 'uint16_t'
  uint16_t cn_len;    /* length of cm_id */
/usr/include/linux/nfsd/cld.h:46:2: error: unknown type name 'uint8_t'
  uint8_t  cm_vers;  /* upcall version */
/usr/include/linux/nfsd/cld.h:47:2: error: unknown type name 'uint8_t'
  uint8_t  cm_cmd;   /* upcall command */
/usr/include/linux/nfsd/cld.h:48:2: error: unknown type name 'int16_t'
  int16_t  cm_status;  /* return code */
/usr/include/linux/nfsd/cld.h:49:2: error: unknown type name 'uint32_t'
  uint32_t cm_xid;   /* transaction id */
/usr/include/linux/nfsd/cld.h:51:3: error: unknown type name 'int64_t'
   int64_t  cm_gracetime; /* grace period start time */

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>