drivers: fuel_gauge: fix i2c_dump_msgs_rw argument

Fix another i2c_dump_msgs_rw:

/drivers/fuel_gauge/bq27z746/emul_bq27z746.c:282:26: warning: passing
argument 1 of ‘i2c_dump_msgs_rw’ from incompatible pointer type

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>