LoongArch: fix vmlinux ld error

LoongArch inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6BWFP

--------------------------------

When CONFIG_DEBUG_INFO_BTF is enabled, ld load error. To
fix this issue, we should use -mdirect-extern-access.
Signed-off-by: NXing Li <lixing@loongson.cn>
Signed-off-by: NHongchen Zhang <zhanghongchen@loongson.cn>
Change-Id: I698169b2af48369d531ef3aa4f9c53b97096da83

arch/loongarch/Makefile

@@ -54,6 +54,7 @@ LDFLAGS_vmlinux			+= -G0 -static -n -nostdlib
 # upgrade the compiler or downgrade the assembler.
 ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS
 cflags-y			+= -mexplicit-relocs
+KBUILD_CFLAGS_KERNEL		+= -mdirect-extern-access
 else
 cflags-y			+= $(call cc-option,-mno-explicit-relocs)
 KBUILD_AFLAGS_KERNEL		+= -Wa,-mla-global-with-pcrel

drivers/firmware/efi/libstub/Makefile

@@ -27,7 +27,7 @@ cflags-$(CONFIG_ARM)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
 cflags-$(CONFIG_RISCV)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
 				   -fpic
 cflags-$(CONFIG_LOONGARCH)	:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
-				   -fpic
+				   -fpie
 
 cflags-$(CONFIG_EFI_GENERIC_STUB) += -I$(srctree)/scripts/dtc/libfdt