Merge remote-tracking branch 'remotes/rth/tags/pull-pa-20200218' into staging

Fixes for Dino and Artist.

# gpg: Signature made Tue 18 Feb 2020 19:35:09 GMT
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth/tags/pull-pa-20200218:
  hw/hppa/dino: Do not accept accesses to registers 0x818 and 0x82c
  hw/hppa/dino: Fix bitmask for the PCIROR register
  hw/hppa/dino: Fix reg800_keep_bits overrun (CID 1419387 1419393 1419394)
  hw/hppa/dino: Add comments with register name
  hw/display/artist: Remove dead code (CID 1419388 & 1419389)
  hw/display/artist: Avoid drawing line when nothing to display
  hw/display/artist: Delay some variables initialization
  hw/display/artist: Remove pointless initialization
  hw/display/artist: Move trace event to draw_line()

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>