npu:phytium: fix build error in phytium_npu_pci_probe

Log:
2025-05-16T15:13:43.6129337Z drivers/staging/phytium-npu/phytium_npu_pci.c:82:16: error: variable 'reg_addr' is used uninitialized whenever 'for' loop exits because its condition is false [-Werror,-Wsometimes-uninitialized]
2025-05-16T15:13:43.6131548Z    82 |         for (bar = 0; bar < NUM_PCI_BARS; bar++) {
2025-05-16T15:13:43.6132195Z       |                       ^~~~~~~~~~~~~~~~~~
2025-05-16T15:13:43.6133127Z drivers/staging/phytium-npu/phytium_npu_pci.c:98:7: note: uninitialized use occurs here
2025-05-16T15:13:43.6134010Z    98 |         if (!reg_addr)
2025-05-16T15:13:43.6134457Z       |              ^~~~~~~~
2025-05-16T15:13:43.6135385Z drivers/staging/phytium-npu/phytium_npu_pci.c:82:16: note: remove the condition if it is always true
2025-05-16T15:13:43.6136692Z    82 |         for (bar = 0; bar < NUM_PCI_BARS; bar++) {
2025-05-16T15:13:43.6137381Z       |                       ^~~~~~~~~~~~~~~~~~
2025-05-16T15:13:43.6138490Z drivers/staging/phytium-npu/phytium_npu_pci.c:52:24: note: initialize the variable 'reg_addr' to silence this warning
2025-05-16T15:13:43.6139510Z    52 |         void __iomem *reg_addr;
2025-05-16T15:13:43.6140038Z       |                               ^
2025-05-16T15:13:43.6140541Z       |                                = NULL
2025-05-16T15:13:43.6141173Z 1 error generated.
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>

Author: opsiff

drivers/staging/phytium-npu/phytium_npu_pci.c

@@ -49,7 +49,7 @@ static int phytium_npu_pci_probe(struct pci_dev *pci_dev,
 {
 	struct phytium_npu_dev *npu_dev;
 	struct device *dev = &pci_dev->dev;
-	void __iomem *reg_addr;
+	void __iomem *reg_addr = NULL;
 	int ret = 0;
         int irq = 0;
         int bar = 0;