runtime selftest: limit kernel hw bp arches

runtime selftest: limit kernel hw bp arches

1. So far, only qemux86[-64] support hw breakpoint, no matter whether or
not with kvm.

qemuppc: The oe-core configuration uses a PPC G4 system as the
default cpu but qemu doesn't simulate the hw breakpoint register for G4.

qemuarm: The arch more than v7 supports hw breakpoint, however arm use
v5 as default.

qemuarm64: We temporarily drop qemuarm64 for the moment. Normally it
will print debug info once, but endlessly when we trigger the break
point. Now it is hard to located the issue, but we will confirm it
later.

qemumips*: Kernel dosen't support hw bp for mips.

2. Syslog maybe not started, so we use dmesg to confirm.

3. Running 'ls' to trigger the hardware breakpoint test.

(From OE-Core rev: 176e50fb177dc40e439700d5f3f838dd7eaaa427)

Signed-off-by: Hongzhi.Song <hongzhi.song@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>