bcachefs: rewrote prefetch asm in gas syntax for clang compatibility

Signed-off-by: Brett Holman <bpholman5@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bset.c

@@ -1181,13 +1181,11 @@ static struct bkey_packed *bset_search_write_set(const struct btree *b,
 
 static inline void prefetch_four_cachelines(void *p)
 {
-#if (CONFIG_X86_64 && !defined(__clang__))
-	asm(".intel_syntax noprefix;"
-	    "prefetcht0 [%0 - 127 + 64 * 0];"
-	    "prefetcht0 [%0 - 127 + 64 * 1];"
-	    "prefetcht0 [%0 - 127 + 64 * 2];"
-	    "prefetcht0 [%0 - 127 + 64 * 3];"
-	    ".att_syntax prefix;"
+#if CONFIG_X86_64
+	asm("prefetcht0 (-127 + 64 * 0)(%0);"
+	    "prefetcht0 (-127 + 64 * 1)(%0);"
+	    "prefetcht0 (-127 + 64 * 2)(%0);"
+	    "prefetcht0 (-127 + 64 * 3)(%0);"
 	    :
 	    : "r" (p + 127));
 #else