flash/str7x: After reset init the flash is unlocked

The default state of the STR7 flash after a reset init is unlocked.
The information in the flash driver now reflects this.

The information about the lock status cannot be read from the
flash chip, so the user is informed that flash info might not
contain accurate information.

[dbrownell@users.sourceforge.net: line length shrinkage]

Signed-off-by: Edgar Grimberg <edgar.grimberg@zylin.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>