remoteproc: stm32: Fix incorrect type in assignment for va

The sparse tool complains about the attribute conversion between
a _iomem void * and a void *:

stm32_rproc.c:122:12: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected void *va @@     got void [noderef] __iomem * @@
stm32_rproc.c:122:12: sparse:     expected void *va
stm32_rproc.c:122:12: sparse:     got void [noderef] __iomem *

Add '__force' to explicitly specify that the cast is intentional.
This conversion is necessary to cast to virtual addresses pointer,used,
by the remoteproc core.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312150052.HCiNKlqB-lkp@intel.com/
Fixes: 13140de0 ("remoteproc: stm32: add an ST stm32_rproc driver")
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Link: https://lore.kernel.org/r/20240117135312.3381936-2-arnaud.pouliquen@foss.st.comSigned-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/remoteproc/stm32_rproc.c

@@ -120,7 +120,7 @@ static int stm32_rproc_mem_alloc(struct rproc *rproc,
 	void *va;
 
 	dev_dbg(dev, "map memory: %pad+%zx\n", &mem->dma, mem->len);
-	va = ioremap_wc(mem->dma, mem->len);
+	va = (__force void *)ioremap_wc(mem->dma, mem->len);
 	if (IS_ERR_OR_NULL(va)) {
 		dev_err(dev, "Unable to map memory region: %pad+0x%zx\n",
 			&mem->dma, mem->len);
@@ -137,7 +137,7 @@ static int stm32_rproc_mem_release(struct rproc *rproc,
 				   struct rproc_mem_entry *mem)
 {
 	dev_dbg(rproc->dev.parent, "unmap memory: %pa\n", &mem->dma);
-	iounmap(mem->va);
+	iounmap((__force __iomem void *)mem->va);
 
 	return 0;
 }