ASoC: fsl_ssi: Remove .num_reg_defaults_raw from regmap_config

This driver provides no .reg_defaults_raw in regmap_config, so
the .num_reg_defaults_raw is useless, and, in fact harmful. It
triggers kernel crash in regmap_init which tries to access the
register defaults.

Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>