zram-perf: Changing zram-perf compressible test pattern

Since zram start supporting to skip compression when hitting
the same pattern in a page, the original test pattern would
not be able to test compression perf. Changing the pattern as
ABCD to get a reasonable test result.

Bug: 119495062
Test: run zram-perf
Change-Id: I58c17687994fa8fe44abe8f32d947b76e434d49a
1 file changed