allow py-breakpoint.exp to work with software watchpoints

allow py-breakpoint.exp to work with software watchpoints

I noticed that the last "maint info breakpoints" test expects the
output to contain:

        .*hw watchpoint.*

But some platforms do not have hw watchpoints (for instance, the
sim on erc32 doesn't).  So I changed the expected output to accept
either.

gdb/testsuite/ChangeLog:

        * gdb.python/py-breakpoint.exp: Fix the expected output of
        one of the "maint info breakpoints" tests to accept the output
        generated on platforms that do not have hardware watchpoints.