* add pinmux driver. hsdk board has arduino, mikrobus and
pmod interfaces, which can be confiured for different function,
such as: gpio, spi, uart, iic.
* add introduction for arduino, mikrobus and pmod interfaces.
Signed-off-by: Watson Zeng <zhiwei@synopsys.com>
This commit includes the initial support of ARC HS Development Kit:
* hsdk soc support
* hsdk board support
* no mmu support, so no userspace
* smp support
Signed-off-by: Wayne Ren <wei.ren@synopsys.com>