The  assignment of the gpio_count and reg_base in ath79_gpio_output_select
takes care that only supported platforms can use ath79_gpio_output_select.
But the rebase of the patches after the last OpenWrt base update
accidentally added an extra check for the SoC which was missing support
soc_is_qca955x().

Boots on QCA955X devices which were using ath79_gpio_output_select stopped
with

    Kernel bug detected[#1]:
    [...]
    Call Trace:
    [<803e6174>] ath79_gpio_output_select+0x30/0xe8
    [<803ed590>] om5p_acv2_setup+0x24/0x200
    [<803e4dc0>] ath79_setup+0x28/0x38
    [<80069ac8>] do_one_initcall+0x148/0x1ec
    [<803e2cc4>] kernel_init_freeable+0x150/0x208
    [<80065218>] kernel_init+0x10/0x114
    [<80060878>] ret_from_kernel_thread+0x14/0x1c

Fixes: a22c1d56 ("Update OpenWrt base")
Signed-off-by: Sven Eckelmann <sven@narfation.org>