staging: fsl-mc: dpmcp opening/closing refactoring

staging: fsl-mc: dpmcp opening/closing refactoring

Before, we were opening and closing a mc_io's dpmcp object
in fsl_mc_portal_reset(), since that was the only function that was
calling dpmcp MC operations. However, it is better for maintainability
to open the dpmcp object when it gets associated with an mc_io object,
and close it when this association is terminated. This way, we are free
to call dpmcp operations on a mc_io's dpmcp object at any time, without
having to check if the dpmcp object is opened or not.

Consequently, the creation/teardown of the association between
an mc_io object and a dpmcp is now encapsulated in two functions:
fsl_mc_io_set_dpmcp()/fsl_mc_io_unset_dpmcp(). Besides, setting
the corresponding pointers for the association, these functions
open and close the dpmcp object respectively.

Signed-off-by: J. German Rivera <German.Rivera@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>