x86/xen: Convert comma to semicolon

Replace a comma between expression statements by a semicolon.

Fixes: 8310b77b ("Xen/gnttab: handle p2m update errors on a per-slot basis")
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20240702031010.1411875-1-nichen@iscas.ac.cn


Signed-off-by: Juergen Gross <jgross@suse.com>