powerpc/ps3: move udbg_shutdown_ps3gelic prototype

powerpc/ps3: move udbg_shutdown_ps3gelic prototype

Allmodconfig kernels produce a missing-prototypes warning:

arch/powerpc/platforms/ps3/gelic_udbg.c:239:6: error: no previous prototype for 'udbg_shutdown_ps3gelic' [-Werror=missing-prototypes]

Move the declaration from a local header to asm/ps3.h where it can be
seen from both the caller and the definition.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Geoff Levand <geoff@infradead.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
[mpe: Drop CONFIG_PS3GELIC_UDBG to fix build error]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231108125843.3806765-18-arnd@kernel.org