Revert Change to MTU Size

[rcarteraz]

WisBlock/bootloader/RAK4630/Latest/WisCore_RAK4631_Bootloader/lib/sdk11/components/libraries/bootloader_dfu/dfu_transport_ble.c

Line 40 in adbeffe

#define BLEGATT_ATT_MTU_MAX 23

WisBlock/bootloader/RAK4630/Latest/WisCore_RAK4631_Bootloader/src/main.c

Line 131 in 8f5ea5e

#define BLEGATT_ATT_MTU_MAX 23

@beegee-tokyo Okay, I think these changes that were recommended in #65 and added in commit adbeffe can be reverted. Based on my testing it's probably a better experience if it is. It appears that Nordic has improved their apps to better handle legacy and secure boot loaders so that this change seems to be no longer necessary.

I've been testing with two devices. One is running 0.4.2 bootloader and the other is running 0.4.3. I find performance is actually better on bootloader 0.4.2. 0.4.3 is now requiring setting PRN to on and turning the packet count to a very low number which is really slow. Whereas with 0.4.3 I can use the stock settings of the DFU app without issue and it runs 2-3x faster.