aries | p1: staging: zram: fix kunmapping order

This patch fixes the unmapping order of KM_USER0/1 in
handle_uncompressed_page() and zram_read() so that kmap()/kunmap() calls
are correctly nested.

Reported-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Reviewed-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Humberto Borba <humberos@gmail.com>
Change-Id: I7ad461816f0ab9e6feff91d2a7ae85619bea943f