media: pci: mgb4: Refactor struct resources

The struct resource end field signifies the end address not the
relative offset from the start field i.e size == (end - start) + 1.

Amend the .end field to specify the end address not the relative size
from the offset as is currently given.

Fixes cocci check:
drivers/media/pci/mgb4/mgb4_regs.c:13:22-25: WARNING: Suspicious code. resource_size is maybe missing with res

Link: https://lore.kernel.org/linux-media/20240429-fix-cocci-v3-1-3c4865f5a4b0@chromium.org
Reviewed-by: Martin Tůma <martin.tuma@digiteqautomotive.com>
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Author: ribalda

drivers/media/pci/mgb4/mgb4_core.c

@@ -493,13 +493,13 @@ static int mgb4_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	struct mgb4_dev *mgbdev;
 	struct resource video = {
 		.start	= 0x0,
-		.end	= 0x100,
+		.end	= 0xff,
 		.flags	= IORESOURCE_MEM,
 		.name	= "mgb4-video",
 	};
 	struct resource cmt = {
 		.start	= 0x1000,
-		.end	= 0x1800,
+		.end	= 0x17ff,
 		.flags	= IORESOURCE_MEM,
 		.name	= "mgb4-cmt",
 	};

drivers/media/pci/mgb4/mgb4_regs.c

@@ -10,7 +10,7 @@
 int mgb4_regs_map(struct resource *res, struct mgb4_regs *regs)
 {
 	regs->mapbase = res->start;
-	regs->mapsize = res->end - res->start;
+	regs->mapsize = resource_size(res);
 
 	if (!request_mem_region(regs->mapbase, regs->mapsize, res->name))
 		return -EINVAL;