[MTD] [NAND] cs553x_nand: command line partitioning support

Implements kernel command line partitioning support for the CS5535/CS5536 chipsets driver.

For that the following is done:

* cs553x_cleanup(): try the cleanup for all chip selects to not leak memory
* Assign a unique name for each chip select to be separately addressable in the command line mtd-id portion(s)
* Use the already defined PIN_OPT_IDE constant where appropriate for readability
* Include command line partitioning support when CONFIG_MTD_PARTS is set

Signed-off-by: Mart Raudsepp <mart.raudsepp@artecdesign.ee>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>