staging: exfat: Remove unused struct 'dev_info_t'

Remove global declaration of unused struct "dev_info_t".
Structure "dev_info_t" is defined in exfat.h and not referenced in any
other file.

Signed-off-by: Pragat Pandya <pragat.pandya@gmail.com>
Link: https://lore.kernel.org/r/20200130101118.15936-3-pragat.pandya@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>