aarch64: Fix LDAPURS assembly output

... And another follow-up once I realised that the sign-extending load, of course,
needs to have strictly an X-reg as a destination for DImode extensions and a W-reg
for SImode ones.

Tested on aarch64-none-linux.

gcc/ChangeLog:

	* config/aarch64/atomics.md (*aarch64_atomic_load<ALLX:mode>_rcpc_sext):
	Use <GPI:w>  for destination format.
	* config/aarch64/iterators.md (w_sz): Delete.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/ldapr-sext.c: Adjust expected output.

gcc/config/aarch64/atomics.md

@@ -723,7 +723,7 @@
          (match_operand:SI 2 "const_int_operand")]			;; model
        UNSPECV_LDAP)))]
   "TARGET_RCPC2 && (<GPI:sizen> > <ALLX:sizen>)"
-  "ldapurs<ALLX:size>\t%<ALLX:w_sx>0, %1"
+  "ldapurs<ALLX:size>\t%<GPI:w>0, %1"
 )
 
 (define_insn "atomic_store<mode>"

gcc/config/aarch64/iterators.md

@@ -1012,10 +1012,6 @@
 ;; 32-bit version and "%x0" in the 64-bit version.
 (define_mode_attr w [(QI "w") (HI "w") (SI "w") (DI "x") (SF "s") (DF "d")])
 
-;; Similar to w above, but used for sign-extending loads where we want to
-;; use %x0 for SImode.
-(define_mode_attr w_sx [(QI "w") (HI "w") (SI "x")])
-
 ;; The size of access, in bytes.
 (define_mode_attr ldst_sz [(SI "4") (DI "8")])
 ;; Likewise for load/store pair.

gcc/testsuite/gcc.target/aarch64/ldapr-sext.c

@@ -24,7 +24,7 @@ test_##name (void)						\
 /*
 **test_s8_s64:
 **...
-**	ldapursb	w0, \[x[0-9]+\]
+**	ldapursb	x0, \[x[0-9]+\]
 **	ret
 */
 
@@ -33,7 +33,7 @@ TEST(s8_s64, s8, long long)
 /*
 **test_s16_s64:
 **...
-**	ldapursh	w0, \[x[0-9]+\]
+**	ldapursh	x0, \[x[0-9]+\]
 **	ret
 */