target/arm/whpx: fix whpx-arm post-reset CPU state

Reset should leave CPU 0 running, and should leave all other CPUs
suspended. Instead, no CPUs are suspended and CPUs may be left in
low-power states.

Fix by updating state in whpx_set_registers WHPX_LEVEL_RESET_STATE.

Signed-off-by: Doug Cook <dcook@microsoft.com>
Reviewed-by: Mohamed Mediouni <mohamed@unpredictable.fr>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit 57197bf183f3afa906f9007de918244adff9ab7e)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>