arm: armv8: Fix warning about redeclaring global functions as weak

As seen with clang-12:
warning: __asm_invalidate_l3_dcache changed binding to STB_WEAK

As we indeed use ENTRY and then declare the function weak manually.  Use
the WEAK declarative from <linux/linkage.h> instead.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/cpu/armv8/cache.S b/arch/arm/cpu/armv8/cache.S
index 443d94c..e04907d 100644
--- a/arch/arm/cpu/armv8/cache.S
+++ b/arch/arm/cpu/armv8/cache.S
@@ -188,27 +188,24 @@
 .popsection
 
 .pushsection .text.__asm_invalidate_l3_dcache, "ax"
-ENTRY(__asm_invalidate_l3_dcache)
+WEAK(__asm_invalidate_l3_dcache)
 	mov	x0, #0			/* return status as success */
 	ret
 ENDPROC(__asm_invalidate_l3_dcache)
-	.weak	__asm_invalidate_l3_dcache
 .popsection
 
 .pushsection .text.__asm_flush_l3_dcache, "ax"
-ENTRY(__asm_flush_l3_dcache)
+WEAK(__asm_flush_l3_dcache)
 	mov	x0, #0			/* return status as success */
 	ret
 ENDPROC(__asm_flush_l3_dcache)
-	.weak	__asm_flush_l3_dcache
 .popsection
 
 .pushsection .text.__asm_invalidate_l3_icache, "ax"
-ENTRY(__asm_invalidate_l3_icache)
+WEAK(__asm_invalidate_l3_icache)
 	mov	x0, #0			/* return status as success */
 	ret
 ENDPROC(__asm_invalidate_l3_icache)
-	.weak	__asm_invalidate_l3_icache
 .popsection
 
 /*