Drivers: hv: Use HV_HYP_PAGE in hv_synic_enable_regs()

Both the base_*_gpa should use the guest page number in Hyper-V page, so
use HV_HYP_PAGE instead of PAGE.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20200916034817.30282-5-boqun.feng@gmail.com


Signed-off-by: Wei Liu <wei.liu@kernel.org>