ARC: [plat-eznps] Add missing struct nps_host_reg_aux_dpc

ARC: [plat-eznps] Add missing struct nps_host_reg_aux_dpc

[ Upstream commit 05b466bf846d2e8d2f0baf8dfd81a42cc933e237 ]

Fixing compilation issue caused by missing struct nps_host_reg_aux_dpc
definition.

Fixes: 3f9cd874dcc87 ("ARC: [plat-eznps] avoid toggling of DPC register")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Ofer Levi <oferle@mellanox.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>