spi: stm32-ospi: Fix NULL vs IS_ERR() bug in stm32_ospi_get_resources()

This code was changed from using devm_ioremap() which returns NULL to
using devm_ioremap_resource() which returns error pointers.  Update
the error checking to match.

Fixes: defe01ab ("spi: stm32-ospi: Use of_reserved_mem_region_to_resource() for "memory-region"")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/fb2a26a2-119b-4b5a-8d44-b29e2c736081@sabinyo.mountain


Signed-off-by: Mark Brown <broonie@kernel.org>