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/arch/nds32/Makefile b/arch/nds32/Makefile
index 031c676..63f4f17 100644
--- a/arch/nds32/Makefile
+++ b/arch/nds32/Makefile
@@ -33,12 +33,12 @@
 ifdef CONFIG_CPU_LITTLE_ENDIAN
 KBUILD_CFLAGS   += $(call cc-option, -EL)
 KBUILD_AFLAGS   += $(call cc-option, -EL)
-LDFLAGS         += $(call cc-option, -EL)
+KBUILD_LDFLAGS  += $(call cc-option, -EL)
 CHECKFLAGS      += -D__NDS32_EL__
 else
 KBUILD_CFLAGS   += $(call cc-option, -EB)
 KBUILD_AFLAGS   += $(call cc-option, -EB)
-LDFLAGS         += $(call cc-option, -EB)
+KBUILD_LDFLAGS  += $(call cc-option, -EB)
 CHECKFLAGS      += -D__NDS32_EB__
 endif