arm64: zynqmp: Remove gpio from aliases list

It is not recommended to have aliases for gpio. In past it was used in
Linux for assigning numbers via sysfs which is deprecated and libgpiod
should be used instead.
In U-Boot this number is used for seq number but gpio offset are not
counted from this number. That's why having these aliases only for seq
number is not needed. As is done in Linux it is the best to use full gpio
name instead of sequence number which depends on sequence in binding.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>