ARC: merge HAPS-HS with nSIM-HS configs

Starting from nSIM 2019.06 is possible to use DW UART
instead of ARC UART. That allows us to merge
"nsim_hs" with "haps_hs" and "nsim_hs_smp" with "haps_hs_smp"
with minor changes which were done in previous commits.

We eliminate nsim_hs_defconfig and nsim_hs_smp_defconfig
and leave haps_hs_defconfig and haps_hs_smp_defconfig
which can be used on HAPS / nSIM / ZEBU / QEMU platforms
without additional changes in Linux kernel.

For nSIM we should now use UART property values
"-prop=nsim_mem-dev=uart0,kind=dwuart,base=0xf0000000"
instead of previously used
"-prop=nsim_mem-dev=uart0,base=0xc0fc1000"
"use_connect" and "irq" values of UART property remains untouched.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>