libc: Fix invalid offset warning with Clang

Change-Id: I71274a6f592356a259ccdbe9c09383bc75e2d26b
diff --git a/libc/arch-arm64/kryo/bionic/memcpy_base.S b/libc/arch-arm64/kryo/bionic/memcpy_base.S
index 0096bb7..ee0757d 100644
--- a/libc/arch-arm64/kryo/bionic/memcpy_base.S
+++ b/libc/arch-arm64/kryo/bionic/memcpy_base.S
@@ -170,8 +170,8 @@
 	add	x10, x1, #(PLDOFFS*PLDSIZE)
 	bic	x10, x10, #0x7F
 	sub	x12, x12, #PLDOFFS
-	prfm	PLDL1KEEP, [x10, #(-1*PLDSIZE)]
-	prfm	PLDL1KEEP, [x10, #(-1*PLDSIZE+64)]
+	prfm	PLDL1KEEP, [x10, #((PLDOFFS-1)*PLDSIZE)]
+	prfm	PLDL1KEEP, [x10, #((PLDOFFS-1)*PLDSIZE)+64]
 	cmp	x12, #(448*1024/128)
 	bhi	kryo_bb_copy_128_loop_ddr