toolbox/modprobe: Fix failure due to blocklist

When a module is blocklisted, LoadWithAliases() will return an error
indicating the module failed to load. When the blocklist is requested
(via the -b parameter), let's not return an error if a blocklisted
module fails to load.

Test: verified lsmod on pixel 6
Bug: 324018983
Change-Id: I68f7d46bf9fd99e4b4e51ef92ea71686907f1125