iio: magnetometer: af8133j: Drop unneeded assignment for cache_type

REGCACHE_NONE is the default type of the cache when not provided.
Drop unneeded explicit assignment to it.

Note, it's defined to 0, and if ever be redefined, it will break
literally a lot of the drivers, so it very unlikely to happen.

Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Nuno Sá <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/magnetometer/af8133j.c

···
 	.reg_bits = 8,
 	.val_bits = 8,
 	.max_register = AF8133J_REG_SWR,
-	.cache_type = REGCACHE_NONE,
 };
 
 static void af8133j_power_down_action(void *ptr)