ARC: add "hweightX" definitions used by NAND driver

We use generic software implemetations.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
ARC: fix Franc's "fix" in 86d39b798bc1edbfcaa6bef7fd527f5722b40601

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
ARC: add support for built-in NAND-controller

Probably there's some hidded HW issue that causes data to written or
read with errors. Need to look at it a bit more.

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