spi: dw-mmio: add error handling for reset_control_deassert()

spi: dw-mmio: add error handling for reset_control_deassert()

Currently reset_control_deassert() is called without checking its
return value. This can lead to silent failures when reset deassertion
fails.

Add proper error handling to:
1. Check the return value of reset_control_deassert()
2. Return the error to the caller
3. Provide meaningful error message using dev_err_probe()

This ensures that reset-related failures are properly reported during
probe and helps with debugging reset issues.

Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
Link: https://patch.msgid.link/20251007101134.1912895-1-a.shimko.dev@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>