arc: clean-up config.mk for arc700

Remove legacy options - there's no need to have them in modern U-boot
for ARC.

We just specify our CPU

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
arc: fix alignment of "relocate_code"

Otherwise jump to address of "relocate_code" caused in exception.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
arc: implememnt separate configurations for LE/BE

 * Add "-EB" for linker
 * Implement proper CROSS_COMPILE settings for endianesses

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