The grub2-install application runs a few grub2-* commands. Two of those,
grub2-bios-setup and grub2-probe, need read/write access to the (fixed) disks.
Mark those two applications as bootloader_exec_t (as is the case with the "grub"
legacy command in the past) allows the commands to continue.
Signed-off-by: Sven Vermeulen <sven.vermeulen@siphos.be>