drm/tinydrm: add driver for ST7735R panels

This adds a new driver for Sitronix ST7735R display panels.

This has been tested using an Adafruit 1.8" TFT.

Signed-off-by: David Lechner <david@lechnology.com>
Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1514833336-22564-4-git-send-email-david@lechnology.com