Remove support for virtual blocks, which are build by
concatenation of multiple physical erase blocks.

For more information please read the MTD mailing list thread
"[PATCH] remove support for virtual blocks"
Signed-off-by: NFerenc Havasi <havasi@inf.u-szeged.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>