Adjust Pentax black level as per previous commit.
Adjust Pentax black level as per previous commit.

anarsoul/rawspeed,mgehre/rawspeed,darktable-org/rawspeed,anarsoul/rawspeed,darktable-org/rawspeed,klauspost/rawspeed,LebedevRI/rawspeed,mgehre/rawspeed,klauspost/rawspeed,LebedevRI/rawspeed,anarsoul/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed,LebedevRI/rawspeed,LebedevRI/rawspeed,darktable-org/rawspeed