src/bootchooser: r_boot_get_state: remove wrong-scoped printout
src/bootchooser: r_boot_get_state: remove wrong-scoped printout

Following the rule that a function must only add error information that
cannot be added by the caller, r_boot_get_state() must not emit "Failed
to get state of %s: ".

Changing this, turns the redundant error output (form install.c):

| Failed to get boot state of rootfs.1: Failed to get state of rootfs.1: Variable B_OK not set in grub environment

into:

| Failed to get boot state of rootfs.1: Variable B_OK not set in grub environment

Signed-off-by: Enrico Jorns <a2e5f936c390f36494e46e71bcfbe365bb1e8c49@pengutronix.de>

ejoerns/rauc,ejoerns/rauc,jluebbe/rauc,ejoerns/rauc,jluebbe/rauc,rauc/rauc,rauc/rauc,jluebbe/rauc,rauc/rauc