lightnvm: merge gennvm with core

For the first iteration of Open-Channel SSDs, it was anticipated that
there could be various media managers on top of an open-channel SSD,
such to allow vendors to plug in their own host-side FTLs, without the
media manager in between.

Now that an Open-Channel SSD is exposed as a traditional block device,
there is no longer a need for this. Therefore lets merge the gennvm code
with core and simplify the stack.

Signed-off-by: Matias Bjørling <matias@cnexlabs.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/lightnvm/Kconfig

@@ -26,15 +26,6 @@ config NVM_DEBUG
 
 	It is required to create/remove targets without IOCTLs.
 
-config NVM_GENNVM
-	tristate "General Non-Volatile Memory Manager for Open-Channel SSDs"
-	---help---
-	Non-volatile memory media manager for Open-Channel SSDs that implements
-	physical media metadata management and block provisioning API.
-
-	This is the standard media manager for using Open-Channel SSDs, and
-	required for targets to be instantiated.
-
 config NVM_RRPC
 	tristate "Round-robin Hybrid Open-Channel SSD target"
 	---help---