ALSA: cs4236: fix error return comparison of an unsigned integer

The return from pnp_irq is an unsigned integer type resource_size_t
and hence the error check for a positive non-error code is always
going to be true.  A check for a non-failure return from pnp_irq
should in fact be for (resource_size_t)-1 rather than >= 0.

Addresses-Coverity: ("Unsigned compared against 0")
Fixes: a9824c8 ("[ALSA] Add CS4232 PnP BIOS support")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20191122131354.58042-1-colin.king@canonical.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/isa/cs423x/cs4236.c

@@ -278,7 +278,8 @@ static int snd_cs423x_pnp_init_mpu(int dev, struct pnp_dev *pdev)
 	} else {
 		mpu_port[dev] = pnp_port_start(pdev, 0);
 		if (mpu_irq[dev] >= 0 &&
-		    pnp_irq_valid(pdev, 0) && pnp_irq(pdev, 0) >= 0) {
+		    pnp_irq_valid(pdev, 0) &&
+		    pnp_irq(pdev, 0) != (resource_size_t)-1) {
 			mpu_irq[dev] = pnp_irq(pdev, 0);
 		} else {
 			mpu_irq[dev] = -1;	/* disable interrupt */