Revert "xen/balloon: Fix crash when ballooning on x86 32 bit PAE"

Revert "xen/balloon: Fix crash when ballooning on x86 32 bit PAE"

This reverts commit 57b02af32dbea7944f3ac502d3625ed5039ba71a.

This has been fixed by commit b8216e73070d6589f71 which added the out
of bounds check to __add_memory, so that trying to add blocks past
MAX_PHYSMEM_BITS will fail.

Note the check in the Xen balloon driver was bogus anyway, as it
checked the start address of the resource, but it should instead test
the end address to assert the whole resource falls below
MAX_PHYSMEM_BITS.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20200727091342.52325-4-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>