gpio: aspeed: fix ast2600 bank properties

GPIO_T is mapped to the most significant byte of input/output mask, and
the byte in "output" mask should be 0 because GPIO_T is input only. All
the other bits need to be 1 because GPIO_Q/R/S support both input and
output modes.

Fixes: ab4a8553

 ("gpio: aspeed: Add in ast2600 details to Aspeed driver")
Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
Reviewed-by: Tao Ren <rentao.bupt@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>