spi/hspi: fixup Runtime PM enable timing

3e00a09d2fbd64f0ad98e7c8c29dbf9e038fc746
(spi/hspi: Convert to core runtime PM)
enabled master->auto_runtime_pm.
Then, pm_runtime_enable() is required *before*
spi_register_master() calling.
This patch fixed it up.
Kernel will hang up with "spi_master spi0: Failed to power device: -13"
message without this patch.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@linaro.org>