ASoC: tas2781: add support for FW version 0x0503

Layout of FW version 0x0503 is compatible with 0x0502.
Already supported by TI's tas2781-linux-driver tree.
https://git.ti.com/cgit/tas2781-linux-drivers/tas2781-linux-driver/

Fixes: 915f5ead

 ("ASoC: tas2781: firmware lib")
Signed-off-by: Gergo Koteles <soyer@irl.hu>
Link: https://msgid.link/r/98d4ee4e01e834af72a1a0bea6736facf43582e0.1702513517.git.soyer@irl.hu
Signed-off-by: Mark Brown <broonie@kernel.org>