x86/PVH: avoid 32-bit build warning when obtaining VGA console info

In the commit referenced below I failed to pay attention to this code
also being buildable as 32-bit. Adjust the type of "ret" - there's no
real need for it to be wider than 32 bits.

Fixes: 934ef33 ("x86/PVH: obtain VGA console info in Dom0")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>

Link: https://lore.kernel.org/r/2d2193ff-670b-0a27-e12d-2c5c4c121c79@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>

Author: jbeulich

arch/x86/xen/enlighten_pvh.c

@@ -48,7 +48,7 @@ void __init xen_pvh_init(struct boot_params *boot_params)
 		struct xen_platform_op op = {
 			.cmd = XENPF_get_dom0_console,
 		};
-		long ret = HYPERVISOR_platform_op(&op);
+		int ret = HYPERVISOR_platform_op(&op);
 
 		if (ret > 0)
 			xen_init_vga(&op.u.dom0_console,