ata: sata_gemini: Add missing MODULE_DESCRIPTION

Add the missing MODULE_DESCRIPTION() to avoid warnings such as:

WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/ata/sata_gemini.o

when compiling with W=1.

Fixes: be4e456e ("ata: Add driver for Faraday Technology FTIDE010")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>