drm/vc4: plane: Change LBM alignment constraint on LBM

The HVS5 needs an alignment of 64bytes for its LBM memory, so let's reflect
it.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://patchwork.freedesktop.org/patch/msgid/6f9c4fe1eb9258a3f1d0f21af6a99c42472ac531.1599120059.git-series.maxime@cerno.tech