Merge patch series "bootstd: Fix efi_mgr usage in bootmeths env var"

Sam Protsenko <semen.protsenko@linaro.org> says:

Defining the 'bootmeths' environment variable with efi_mgr causes NULL
pointer dereference when running 'bootflow scan' on the E850-96 board.
This patch series fixes that, and cleans up the surrounding code a
little while at it.

Link: https://lore.kernel.org/r/20250112034213.13153-1-semen.protsenko@linaro.org