rockchip: rk3588-evb: Update defconfig

Update defconfig for rk3588-evb with new defaults.

Add CONFIG_SPL_FIT_SIGNATURE=y to let SPL verify an auto generated hash
of FIT images. This help indicate if there is an issue loading any of
the images to DRAM or SRAM.

Extend SPL_MAX_SIZE to 0x40000, SPL is loaded to 0x0 and TF-A is loaded
to 0x40000, use the space in between as SPL_MAX_SIZE.

Add config options to include useful gpio and regulator cmd.

Remove the CONFIG_NET_RANDOM_ETHADDR=y option, ethaddr and eth1addr is
set based on cpuid read from OTP.

Remove CONFIG_DEBUG_UART_ANNOUNCE=y to remove debug messages.

Add CONFIG_SYS_NS16550_MEM32=y to use 32bit access of serial register.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>