s390: use -fPIC for module compile

The xfs module uses a lot of tracepoint, with TRACEPOINTS=y and a
few debugging options the GOT table of the xfs module will get
bigger than 4K. To get a working xfs module it needs to be compiled
with -fPIC instead of -fpic. To play safe use -fPIC for all modules.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Makefile

@@ -24,8 +24,8 @@ CHECKFLAGS	+= -D__s390__ -msize-long
 else
 LD_BFD		:= elf64-s390
 LDFLAGS		:= -m elf64_s390
-KBUILD_AFLAGS_MODULE += -fpic -D__PIC__
-KBUILD_CFLAGS_MODULE += -fpic -D__PIC__
+KBUILD_AFLAGS_MODULE += -fPIC
+KBUILD_CFLAGS_MODULE += -fPIC
 KBUILD_CFLAGS	+= -m64
 KBUILD_AFLAGS	+= -m64
 UTS_MACHINE	:= s390x