[MTD] [NAND] Fix refactoring of EDB7312 hwcontrol function.

The patch ensures that the current code (kernel 2.6.22) uses the bits
like the code prior to the refactoring. The variable "bits" is employed
in a useful way now.

Signed-off-by: Roland Stigge <stigge@antcom.de>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>