fs_mgr: Fix ZRAM error when ZRAM disk size beyond (2^31-1) bytes

Because the zram_size type is unsigned int.so if ZRAM size great
than 2^31 -1, zram_fp will receive a negtive integer, while the
ZRAM driver only accept natural number.We need to use printf
formatting %u instand of %d.

Test: 1. Config the zramdisk size 2348810240 and build a ramdisk
      2. Reflash device and check below command:
         $adb shell dumpsys meminfo
         $ adb shell cat /sys/block/zram0/disksize
         ZRAM info display will be abnormal
      3. Config the zramdisk size 2348810240 and apply with this
         patch.
      4. Retest to step 2 and the ZRAM info will be ok.

Change-Id: I473de33fbd0b66cf13eac3172684e9fef11b6ef0