losetup: remove the --verbose flag, as it doesn't actually do anything

losetup: remove the --verbose flag, as it doesn't actually do anything

Fourteen years ago, commit c7e0925def rewrote the `losetup` tool,
removing all references to the 'verbose' variable.  Three years
later, commit 60cb2c3720 removed the line 'verbose = 1' because
the compiler complained that the variable was set but never used.

Signed-off-by: Benno Schulenberg <bensberg@telfort.nl>