configs: set CONFIG_LMB_MAX_REGIONS=64 for all mt798[16] boards

With recently added wireless offloading features in Linux [1] the
number of reserved memory regions with MediaTek SoCs supporting
offloading wireless-to-Ethernet traffic grew beyond the default (8)
which breaks booting Linux:
ERROR: Failed to allocate 0xa6ac bytes below 0xc0000000.
device tree - allocation error
FDT creation failed!
resetting ...

Raise CONFIG_LMB_MAX_REGIONS to 64 like it is already done for other
SoCs which require a larger number of reserved memory regions, eg.
exynos78x0 based a3y17lte, a5y17lte and a7y17lte or dragonboard845c.

[1]: https://lore.kernel.org/netdev/e3489a697b404bd47447190cd2e5adf090ae61c2.1667687249.git.lorenzo@kernel.org/
     https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=eed4f1ddad8c5ad7596b229caec8bd7b477b81ee

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
diff --git a/configs/mt7981_sd_rfb_defconfig b/configs/mt7981_sd_rfb_defconfig
index 17592dc..85be9bb 100644
--- a/configs/mt7981_sd_rfb_defconfig
+++ b/configs/mt7981_sd_rfb_defconfig
@@ -62,3 +62,4 @@
 CONFIG_FAT_WRITE=y
 CONFIG_HEXDUMP=y
 # CONFIG_EFI_LOADER is not set
+CONFIG_LMB_MAX_REGIONS=64