staging: fsl-mc: dprc: shorten DPRC interrupt name

improve readibility of the DPRC interrupt name in sysfs by
shortening this and just using the device name.  There is only
one interrupt DPRC used, so no further differentiation is needed.

Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>