mke2fs: make "invalid blocks count" error more clear

mke2fs: make "invalid blocks count" error more clear

Mistakes on the commandline can lead to odd error messages:

# mke2fs -t ext4 -E stride=128 stripe-width=512 /dev/sda1
mke2fs: invalid blocks count - /dev/sda1

Making it a bit more explicit is more obvious:

mke2fs: invalid blocks count '/dev/sda1' on device 'stripe-width=512'

(hint, the mistake was no comma separation for -E)

Reported-by: Adam Huffman <bloch@verdurin.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>