fastboot: f2fs: handle return code correctly

The f2fs shares the fsck return code for sload.f2fs, since it calls fsck after
loading files.

enum {
	FSCK_SUCCESS                 = 0,
	FSCK_ERROR_CORRECTED         = 1 << 0,
	FSCK_SYSTEM_SHOULD_REBOOT    = 1 << 1,
	FSCK_ERRORS_LEFT_UNCORRECTED = 1 << 2,
	FSCK_OPERATIONAL_ERROR       = 1 << 3,
	FSCK_USAGE_OR_SYNTAX_ERROR   = 1 << 4,
	FSCK_USER_CANCELLED          = 1 << 5,
	FSCK_SHARED_LIB_ERROR        = 1 << 7,
};

Bug: 176471360
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Change-Id: I06289670834f29a59e704e772791f12328a073f8