frv: add module.h to mb93090-mb00/flash.c to avoid compile fail

This file is built off of a tristate Kconfig option and also contains
modular function calls so it should explicitly include module.h to
avoid compile breakage during header shuffles done in the future.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>