leds: lm3601x: 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: Mark Brown <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Lee Jones <[e-mail]>

drivers/leds/flash/leds-lm3601x.c

···
 	.max_register = LM3601X_DEV_ID_REG,
 	.reg_defaults = lm3601x_regmap_defs,
 	.num_reg_defaults = ARRAY_SIZE(lm3601x_regmap_defs),
-	.cache_type = REGCACHE_RBTREE,
+	.cache_type = REGCACHE_MAPLE,
 	.volatile_reg = lm3601x_volatile_reg,
 };