mtd: devices: elm: Removes <xx> literals in elm DT node

As part of removing generalized dependency, replace <xx> literal fields
in DT compatible field with <52> for am335x platforms.

Signed-off-by: Philip Avinash <avinashphilip@ti.com>
Acked-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>