staging: most: dim2: Remove function dimcb_io_read()

Remove function dimcb_io_read as it does nothing except call inbuilt
function readl.
Modify call sites accordingly.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190708064145.3250-2-nishkadg.linux@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>