zram: Disable allocation failure logging

Disable the logging of errors when allocations fail
for zram pages. This avoid excessive logging when system is
very low on memory.

Change-Id: Ifabcf8f1b9c3e3717599d6a0a924f7b2061f00ea
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>