kbuild: rename LDFLAGS to KBUILD_LDFLAGS

Commit a0f97e06a43c ("kbuild: enable 'make CFLAGS=...' to add
additional options to CC") renamed CFLAGS to KBUILD_CFLAGS.

Commit 222d394d30e7 ("kbuild: enable 'make AFLAGS=...' to add
additional options to AS") renamed AFLAGS to KBUILD_AFLAGS.

Commit 06c5040cdb13 ("kbuild: enable 'make CPPFLAGS=...' to add
additional options to CPP") renamed CPPFLAGS to KBUILD_CPPFLAGS.

For some reason, LDFLAGS was not renamed.

Using a well-known variable like LDFLAGS may result in accidental
override of the variable.

Kbuild generally uses KBUILD_ prefixed variables for the internally
appended options, so here is one more conversion to sanitize the
naming convention.

I did not touch Makefiles under tools/ since the tools build system
is a different world.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 4bf811c..c8cf453 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -75,7 +75,7 @@
 		${KBUILD_VMLINUX_LIBS}				\
 		--end-group"
 
-	${LD} ${LDFLAGS} -r -o ${1} ${objects}
+	${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
 }
 
 # Link of vmlinux
@@ -95,7 +95,7 @@
 			--end-group				\
 			${1}"
 
-		${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}	\
+		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}	\
 			-T ${lds} ${objects}
 	else
 		objects="-Wl,--whole-archive			\