uboot-phytec

arc: hard-code CONFIG_SYS_GENERIC_BOARD into asm/config.h

There're no other options for ARC except "generic board" so ther's no
point to define CONFIG_SYS_GENERIC_BOARD per board.

We now have it set fo all ARC boards.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>