gpio: shared: don't allocate the lookup table until we really need it

gpio: shared: don't allocate the lookup table until we really need it

We allocate memory for the GPIO lookup table at the top of
gpio_shared_add_proxy_lookup() but we don't use it until the very end.
Depending on the timing, we may return earlier. Move the allocation
towards the end.

Fixes: a060b8c511ab ("gpiolib: implement low-level, shared GPIO support")
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20260106-gpio-shared-fixes-v2-3-c7091d2f7581@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>