s390: Always use "long" for ssize_t to match size_t

On s390x-linux-gcc, __SIZE_TYPE__ expands to "long unsigned int" for both
32-bit s390 and 64-bit s390x, as
gcc-4.6.3-nolibc/s390x-linux/lib/gcc/s390x-linux/4.6.3/plugin/include/config/s390/linux.h
has

    #define SIZE_TYPE (TARGET_64BIT ? "long unsigned int" : "long unsigned int")

To match this, __kernel_size_t is always set to "long unsigned int".

But while __kernel_ssize_t is "long" on 64-bit s390x, it is "int" on 32-bit
s390, causing compiler warnings like:

    fs/quota/quota_tree.c:372:4: warning: format '%zd' expects argument of type 'signed size_t', but argument 4 has type 'ssize_t' [-Wformat]

To fix this, __kernel_ssize_t should be "long", irrespective of word size.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/posix_types.h

@@ -13,6 +13,7 @@
  */
 
 typedef unsigned long   __kernel_size_t;
+typedef long            __kernel_ssize_t;
 #define __kernel_size_t __kernel_size_t
 
 typedef unsigned short	__kernel_old_dev_t;
@@ -25,7 +26,6 @@ typedef unsigned short  __kernel_mode_t;
 typedef unsigned short  __kernel_ipc_pid_t;
 typedef unsigned short  __kernel_uid_t;
 typedef unsigned short  __kernel_gid_t;
-typedef int             __kernel_ssize_t;
 typedef int             __kernel_ptrdiff_t;
 
 #else /* __s390x__ */
@@ -35,7 +35,6 @@ typedef unsigned int    __kernel_mode_t;
 typedef int             __kernel_ipc_pid_t;
 typedef unsigned int    __kernel_uid_t;
 typedef unsigned int    __kernel_gid_t;
-typedef long            __kernel_ssize_t;
 typedef long            __kernel_ptrdiff_t;
 typedef unsigned long   __kernel_sigset_t;      /* at least 32 bits */