Revert "Fixed the issue of having an unbootable system when the root filesystem on USB."

This reverts commit 454d440fae1594e2a65c2c84ab49c085e6d0754f.
Revert "Fixed installation of 'raspberrypi-bootloader-nokernel' package."

This reverts commit 82588931c2cfdb352c5eda7d8949960f0251aaf2.