x86/hyperv/vtl: Correct x86_init.mpparse.parse_smp_cfg assignment

VTL platform uses DeviceTree for fetching SMP configuration, assign
the correct parsing function x86_dtb_parse_smp_config() for it to
parse_smp_cfg.

Fixes: c22e19cd ("x86/hyperv/vtl: Prepare for separate mpparse callbacks")
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/1712068830-4513-2-git-send-email-ssengar@linux.microsoft.com