UBI: Change the default percentage of reserved PEB
The actual value (1%) is too low for actual NAND devices, a huge
majority of device has 2% maximum bad blocks (SLC or MLC).
(Actually it's 20 blocks on a 1024 blocks device, 40/2048...)
Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Richard Genoud