staging: unisys: Fix VMCALL_CHANNEL_VERSION_MISMATCH_PARAMS

Get rid of the typedef for VMCALL_CHANNEL_VERSION_MISMATCH_PARAMS, and
use the name struct vmcall_channel_version_mismatch_params instead. Fix
CamelCase member names:

ChannelName => chname
ItemName => item_name
SourceFileName => file_name
SourceLineNumber => line_no

And get rid of the lengthof macro in issue_vmcall_channel_mismatch().

Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>