panel: simple: Fix size and bpp of BOE NV133FHM-N61

The BOE NV133FHM-N61 is documented in the original commit to be a
13.3" panel, but the size listed in our struct doesn't match.
Specifically:

  math.sqrt(30.0 * 30.0 + 18.7 * 18.7) / 2.54 ==> 13.92

Searching around on the Internet shows that the size that was in the
structure was the "Outline Size", not the "Display Area".  Let's fix
it.

Also the Internet says that this panel supports 262K colors.  That's
6bpp, not 8bpp.

Fixes: b0c664cc ("panel: simple: Add BOE NV133FHM-N61")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200508155859.1.I4d29651c0837b4095fb4951253f44036a371732f@changeid