soc: ti: fix wkup_m3_rproc_boot_thread return type

soc: ti: fix wkup_m3_rproc_boot_thread return type

The wkup_m3_rproc_boot_thread() function uses a nonstandard prototype,
which broke after Eric's recent cleanup:

drivers/soc/ti/wkup_m3_ipc.c: In function 'wkup_m3_rproc_boot_thread':
drivers/soc/ti/wkup_m3_ipc.c:429:16: error: 'return' with a value, in function returning void [-Werror=return-type]
  429 |         return 0;
      |                ^
drivers/soc/ti/wkup_m3_ipc.c:416:13: note: declared here
  416 | static void wkup_m3_rproc_boot_thread(struct wkup_m3_ipc *m3_ipc)
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~

Change it to the normal prototype as it should have been from the
start.

Fixes: 111e70490d2a ("exit/kthread: Have kernel threads return instead of calling do_exit")
Fixes: cdd5de500b2c ("soc: ti: Add wkup_m3_ipc driver")
Signed-off-by: Arnd Bergmann <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Acked-by: Santosh Shilimkar <[email protected]>
Acked-by: Tony Lindgren <[email protected]>
Signed-off-by: Eric W. Biederman <[email protected]>