arm64: dts: mt7986: use size of reserved partition for bl2

To store uncompressed bl2 more space is required than partition is
actually defined.

There is currently no known usage of this reserved partition.
Openwrt uses same partition layout.

We added same change to u-boot with commit d7bb1099 [1].

[1] https://source.denx.de/u-boot/u-boot/-/commit/d7bb109900c1ca754a0198b9afb50e3161ffc21e

Cc: stable@vger.kernel.org
Fixes: 8e01fb15b815 ("arm64: dts: mt7986: add Bananapi R3")
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Daniel Golle <daniel@makrotopia.org>
Link: https://lore.kernel.org/r/20230528113343.7649-1-linux@fw-web.de
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

arm64: dts: mt7986: add Bananapi R3

Add support for Bananapi R3 SBC.

- SD/eMMC support (switching first 4 bits of data-bus with sw6/D)
- SPI-NAND/NOR support (switched CS by sw5/C)
- all rj45 ports and both SFP working (eth1/lan4)
- all USB-Ports + SIM-Slot tested
- i2c and all uarts tested
- wifi tested (with eeprom calibration data)

The device can boot from all 4 storage options. Both, SPI and MMC, can
be switched using hardware switches on the board, see
https://wiki.banana-pi.org/Banana_Pi_BPI-R3#Jumper_setting

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Link: https://lore.kernel.org/r/20230106152845.88717-6-linux@fw-web.de
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>