ath10k: pci: Fix comment on ath10k_pci_dump_memory_sram

The description of ath10k_pci_dump_memory_sram() is inaccurate, an error
can never be returned, it is always the length. Update the comment to
reflect.

Fixes: 219cc084 ("ath10k: add memory dump support QCA9984")
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath10k/pci.c

@@ -1578,7 +1578,7 @@ static int ath10k_pci_set_ram_config(struct ath10k *ar, u32 config)
 	return 0;
 }
 
-/* if an error happened returns < 0, otherwise the length */
+/* Always returns the length */
 static int ath10k_pci_dump_memory_sram(struct ath10k *ar,
 				       const struct ath10k_mem_region *region,
 				       u8 *buf)