qcom: hyp_core_ctl: Get reserve CPUs from Hypervisor

Hypervisor provides system call interface for getting/setting
the virtual CPU to physical CPU mappings used for the other
guests. Use of this interface to get the physical CPUs to be
reserved for the other guest when reservation is enabled.
The system call requires resource ids as arguments to refer the
virtual CPUs. Convert the driver to a platform driver to receive
these resource ids from the device tree.

Since the reserve CPUs are obtained dynamically from the hypervisor
system calls, remove the support for obtaining the reserve CPUs from
kernel config.

This patch also limits the number of CPUs that can be reserved to
half of the possible CPUs to make sure that the guest running this
driver is not starved.

Change-Id: Icfbbc9972936926d65a457e369b192334e2725bd
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>