fix(asm): set the CASALH opcode bit fifteen

The CASALH entry carried the CASB/CASH opcode pattern where the acquire
forms take the full fixed field, so the word differed from the
toolchain's in one opcode bit.  Pinned against the oracle word.

Assisted-by: GLM 5.3 Flash

asm/arm64_encode.go

@@ -823,7 +823,7 @@ func init() {
 		"CASLH":    0x48a0fc00,
 		"CASAW":    0x88e07c00,
 		"CASAD":    0xc8e07c00,
-		"CASALH":   0x48e07c00,
+		"CASALH":   0x48e0fc00,
 		"LDADDALD": 0xf8e00000,
 		"LDADDALW": 0xb8e00000,
 		"LDADDAD":  0xf8a00000,