multi sector erase and write broken

[mdmillerii]

When fw_setenv tries to erase the whole 128kB environment with one ioctl call the erase gails and the flash status register shows programming error status. Breaking the erase command into erase blocks should be handled by the spi-nor layer but is not working as of 4.3.

The busybox flash_cp command always uses one erase block per system call and is ok. The workaround is to copy the environment to ram in init and back if different at shutdown in the initramfs layer.

Note this also unifies /etc/fw_env.cfg at the cost of no redundant env support and lack of update on crash.

[shenki]

@mdmillerii is this still an issue that needs to be tracked?