zram: add zram size property

Bug: 200899926
Test: check zram swap and backing device
Signed-off-by: Martin Liu <liumartin@google.com>
Change-Id: Ife748938f5e7cfb34c343a3f568c93824f33e8fe
Merged-In: Ife748938f5e7cfb34c343a3f568c93824f33e8fe
3 files changed