tgsi: Make ureg_DECL_output_masked definition match its declaration

tgsi: Make ureg_DECL_output_masked definition match its declaration

Pointed out by GCC 13:

../src/gallium/auxiliary/tgsi/tgsi_ureg.c:483:1: warning: conflicting types for ‘ureg_DECL_output_masked’ due to enum/integer mismatch; have ‘struct ureg_dst(struct ureg_program *, unsigned int,  unsigned int,  unsigned int,  unsigned int,  unsigned int)’ [-Wenum-int-mismatch]
  483 | ureg_DECL_output_masked(struct ureg_program *ureg,
      | ^~~~~~~~~~~~~~~~~~~~~~~
In file included from ../src/gallium/auxiliary/tgsi/tgsi_ureg.c:32:
../src/gallium/auxiliary/tgsi/tgsi_ureg.h:245:1: note: previous declaration of ‘ureg_DECL_output_masked’ with type ‘struct ureg_dst(struct ureg_program *, enum tgsi_semantic,  unsigned int,  unsigned int,  unsigned int,  unsigned int)’
  245 | ureg_DECL_output_masked(struct ureg_program *,
      | ^~~~~~~~~~~~~~~~~~~~~~~

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22517>