mediatek: mt7623: phase out uImage.FIT partition parser

Use the new fitblk driver on the BananaPi R2 as well as UniElec U7623.
Introduce boot device selection for fitblk's /chosen/rootdisk
handle, similar to how it is already done on MT7622, MT7986 and MT7988.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

package/boot/uboot-mediatek/patches/302-mt7623-generic-reset-button-ignore-env.patch

@@ -1,6 +1,6 @@
 --- a/board/mediatek/mt7623/mt7623_rfb.c
 +++ b/board/mediatek/mt7623/mt7623_rfb.c
-@@ -4,8 +4,17 @@
+@@ -4,9 +4,18 @@
   */
  
  #include <common.h>
@@ -9,6 +9,7 @@
 +#include <env.h>
 +#include <init.h>
  #include <mmc.h>
+ #include <part.h>
  #include <asm/global_data.h>
 +#include <linux/delay.h>
 +
@@ -18,8 +19,8 @@
  
  DECLARE_GLOBAL_DATA_PTR;
  
-@@ -41,3 +50,25 @@ int mmc_get_env_dev(void)
- 	return mmc_get_boot_dev();
+@@ -60,3 +69,25 @@ int mmc_get_env_dev(void)
+ 	return dev_seq(dev);
  }
  #endif
 +