Use new driver debug macros

This is in preparation for moving the debug argument from driver to device.
New macros:
* fbtft_par_dbg() - Used in FBTFT operations
* fbtft_init_dbg() - used in probe() and remove()

Remove debug ouput from module init/exit.
move 'debug' argument from driver to device

Also add 'debug' argument to fbtft module. This way it's possible to turn on
debugging during boot if the modules is built-in.
remove empty debug macros
fbtft: change debug macros

Use fbtft_par_dbg where possible.
Change macro name: fbtft_fbtft_dev_dbg -> fbtft_dev_dbg
Fix 2 places where debug hex output was missing.
fbtft: fix hex debug output function
fbtft_device: add debug argument
add FBTFT_REGISTER_DRIVER macro
fb_st7735r: add generic ST7735R driver
fbtft: respect display->backlight
fb_st7735r: use static for display struct and don't enable backlight
fb_pcd8544: add generic PCD8544 driver
fbtft_device: honour pdata->bgr set by display section
fbtft: add fbtft_write_reg8_bus9() and fbtft_write_spi_emulate_9()
fb_hx8340bn: add generic HX8340bn driver
fbtft: fbtft_probe_common() support 9-bit SPI emulation setup
fb_hx8340bn: use FBTFT_REGISTER_DRIVER()
fb_ili9341: add generic ILI9341 support
fb_ili9325: add generic ILI9325 driver
fb_ili9325: correct gamma comment
fbtft: fbtft_verify_gpios() honour startbyte