net: ieee802154: at86rf230: 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: Bo Liu <[e-mail]>
Reviewed-by: Miquel Raynal <[e-mail]>
Message-ID: <[e-mail]>
Signed-off-by: Stefan Schmidt <[e-mail]>

drivers/net/ieee802154/at86rf230.c

···
 	.val_bits = 8,
 	.write_flag_mask = CMD_REG | CMD_WRITE,
 	.read_flag_mask = CMD_REG,
-	.cache_type = REGCACHE_RBTREE,
+	.cache_type = REGCACHE_MAPLE,
 	.max_register = AT86RF2XX_NUMREGS,
 	.writeable_reg = at86rf230_reg_writeable,
 	.readable_reg = at86rf230_reg_readable,