xen: Fix inconsistent callers of panic()

xen: Fix inconsistent callers of panic()

Callers are inconsistent with whether they pass a newline to panic(),
including adjacent calls in the same function using different styles.

painc() not expecting a newline is inconsistent with most other printing
functions, which is most likely why we've gained so many inconsistencies.

Switch panic() to expect a newline, and update all callers which currently
lack a newline to include one.

This actually reduces the size of .rodata (0x07e3e8 down to 0x07e3a8) because
a number of strings are passed to both panic() and printk().  As they
previously differed by \n alone, they couldn't be merged.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <julien.grall@arm.com>