FROMLIST: f2fs: fix the msg data type

Data type of msg in f2fs_write_checkpoint trace should
be const char * instead of char *.

Bug: 257879905
Link: https://lore.kernel.org/lkml/1666861961-12924-2-git-send-email-quic_mojha@quicinc.com/


Change-Id: I005fa2adf76cb29d60707d9a96cb2de13dcc6876
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Wasim Nazir <quic_wasimn@quicinc.com>