Add support of secondary boot address for imx8mn. The secondary
boot address is hardcoded in the fuse. The value is calculated
from there according to the following description:
The fuse IMG_CNTN_SET1_OFFSET (0x490[22:19]) is defined as follows:
- Secondary boot is disabled if fuse value is bigger than 10, n = fuse
value bigger than 10.
- n == 0: Offset = 4MB
- n == 2: Offset = 1MB
- Others & n <= 10 : Offset = 1MB*2^n
- For FlexSPI boot, the valid values are: 0, 1, 2, 3, 4, 5, 6, and 7.
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
02737ac86d