Pass to get_linux_inferior_data the inferior for which we want to obtain
the linux-specific data, rather than assuming the current inferior.
This helps slightly reduce the diff in the upcoming main patch.

Update the sole caller to pass the current inferior.

gdb/ChangeLog:

	* linux-tdep.c (get_linux_inferior_data): Add inferior
	parameter.
	(linux_vsyscall_range): Pass current inferior.

Change-Id: Ie4b61190e4a2e89b5b55a140cfecd4de66d92393