mips: Fix KBUILD_CPPFLAGS definition

The KBUILD_CPPFLAGS variable is no longer passed to sh -c 'gcc ...',
but exported and used by the link-vmlinux.sh script. This means that the
double-quotes will not be evaluated by the shell.
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

arch/mips/Makefile

@@ -219,8 +219,8 @@ endif
 
 KBUILD_AFLAGS	+= $(cflags-y)
 KBUILD_CFLAGS	+= $(cflags-y)
-KBUILD_CPPFLAGS += -D"VMLINUX_LOAD_ADDRESS=$(load-y)"
-KBUILD_CPPFLAGS += -D"DATAOFFSET=$(if $(dataoffset-y),$(dataoffset-y),0)"
+KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y)
+KBUILD_CPPFLAGS += -DDATAOFFSET=$(if $(dataoffset-y),$(dataoffset-y),0)
 
 LDFLAGS			+= -m $(ld-emul)