xen/arm: alternative: Remove unused parameter for alternative_if_not_cap

xen/arm: alternative: Remove unused parameter for alternative_if_not_cap

The macro alternative_if_not_cap is taking two parameters. The second
parameter is never used and it is hard to see how this can be used
correctly as it is only protecting the alternative section magic.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Volodymyr Babchuk <volodymyr.babchuk@epam.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>
Release-acked-by: Juergen Gross <jgross@suse.com>