linux-imx

xen/hvc: Fix error cases around HVM_PARAM_CONSOLE_PFN

We weren't resetting the parameter to be passed in to a
known default. Nor were we checking the return value of
hvm_get_parameter.

CC: stable@kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>