kmp204x: implement workaround for A-006559

According to the errata, some bits of an undocumented register in the
DCSR must be set for every core in order to avoid a possible data or
instruction corruption.

This is required for the 2.0 revision of the P2041 that should be used
as soon as available in our design.

Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
Reviewed-by: York Sun <yorksun@freescale.com>