ARC: rename Zebu platform support to HAPS

There are more ARC Linux HAPS users than Zebu ones.

Same kernel would work fine on both, even with embedded DT, assuming the FPGA
bitfile configuration is same

Suggested-by: Francois Bedard <fbedard@ynopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>