sunxi: move CONFIG_SYS_TEXT_BASE out of defconfigs

sunxi: move CONFIG_SYS_TEXT_BASE out of defconfigs

Commit 278b90ce786f ("configs: Migrate CONFIG_SYS_TEXT_BASE") made
CONFIG_SYS_TEXT_BASE a proper Kconfig variable, with the consequence
of moving the common definition shared by almost every sunxi board
into 123 individual defconfig files. But the U-Boot start address
for Allwinner boards is a platform decision which has been around for
ages, so defining it in each *board* config file seems a bit over the
top.
Define the standard values (160MB into DRAM for most SoCs, with two
SoC exceptions) if ARCH_SUNXI is selected, and delete the lines from
the individual defconfigs.

Signed-off-by: Andre Przywara <[email protected]>
Acked-by: Maxime Ripard <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>