spi: wpcm-fiu: Fix potential NULL pointer dereference in wpcm_fiu_probe()

In the Linux kernel, the following vulnerability has been resolved:

spi: wpcm-fiu: Fix potential NULL pointer dereference in wpcm_fiu_probe()

platform_get_resource_byname() can return NULL, which would cause a crash

when passed the pointer to resource_size().

Move the fiu->memory_size assignment after the error check for

devm_ioremap_resource() to prevent the potential NULL pointer dereference.