cxl: Force psl data-cache flush during device shutdown

[ Upstream commit d7b1946c7925a270062b2e0718aa57b42ba619c0 ]

This change adds a force psl data cache flush during device shutdown
callback. This should reduce a possibility of psl holding a dirty
cache line while the CAPP is being reinitialized, which may result in
a UE [load/store] machine check error.

Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>