iio: light: apds9306: convert to use maple tree register cache

The maple tree register cache is based on a much more modern data structure
than the rbtree cache and makes optimisation choices which are probably
more appropriate for modern systems than those made by the rbtree cache.

Signed-off-by: Chu Guangqing <[e-mail]>
Acked-by: Subhajit Ghosh <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/light/apds9306.c

···
 	.volatile_table = &apds9306_volatile_table,
 	.precious_table = &apds9306_precious_table,
 	.max_register = APDS9306_ALS_THRES_VAR_REG,
-	.cache_type = REGCACHE_RBTREE,
+	.cache_type = REGCACHE_MAPLE,
 };
 
 static const struct reg_field apds9306_rf_sw_reset =