memshare: Pass device structure to ramdump driver

The ramdump driver uses the device pointer during ramdump read.
This change passes in the device pointer for memshare during
ramdump create and moves the call to the probe function.

CRs-Fixed: 1079523
Change-Id: I687696dbedfa0ce7e6053d70291a7beb6f81f82e
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>