Staging: nvec: use !x instead of x == NULL

Functions like devm_kzalloc, kmalloc_array, devm_ioremap,
usb_alloc_urb, alloc_netdev return NULL as a return value on failure.
Generally, When NULL represents failure, !x is commonly used.

This patch cleans up the tests on the results of these functions, thereby
using !x instead of x == NULL or NULL == x. This is done via following
coccinelle script:
@prob_7@
identifier x;
statement S;
@@

(
 x = devm_kzalloc(...);
|
 x = usb_alloc_urb(...);
|
 x = kmalloc_array(...);
|
 x = devm_ioremap(...);
|
 x = alloc_netdev(...);
)
 ...
- if(NULL == x)
+ if(!x)
        S
Further we have used isomorphism characteristics of coccinelle to
indicate x == NULL and NULL == x are equivalent. This is done via
following iso script.

Expression
@ is_null @ expression X; @@
X == NULL <=> NULL == X

Signed-off-by: Somya Anand <somyaanand214@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/nvec/nvec.c

@@ -803,7 +803,7 @@ static int tegra_nvec_probe(struct platform_device *pdev)
 	}
 
 	nvec = devm_kzalloc(&pdev->dev, sizeof(struct nvec_chip), GFP_KERNEL);
-	if (nvec == NULL)
+	if (!nvec)
 		return -ENOMEM;
 
 	platform_set_drvdata(pdev, nvec);

drivers/staging/nvec/nvec_paz00.c

@@ -51,7 +51,7 @@ static int nvec_paz00_probe(struct platform_device *pdev)
 	int ret = 0;
 
 	led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
-	if (led == NULL)
+	if (!led)
 		return -ENOMEM;
 
 	led->cdev.max_brightness = NVEC_LED_MAX;

drivers/staging/nvec/nvec_power.c

@@ -378,7 +378,7 @@ static int nvec_power_probe(struct platform_device *pdev)
 	struct nvec_chip *nvec = dev_get_drvdata(pdev->dev.parent);
 
 	power = devm_kzalloc(&pdev->dev, sizeof(struct nvec_power), GFP_NOWAIT);
-	if (power == NULL)
+	if (!power)
 		return -ENOMEM;
 
 	dev_set_drvdata(&pdev->dev, power);

drivers/staging/nvec/nvec_ps2.c

@@ -109,7 +109,7 @@ static int nvec_mouse_probe(struct platform_device *pdev)
 	char mouse_reset[] = { NVEC_PS2, SEND_COMMAND, PSMOUSE_RST, 3 };
 
 	ser_dev = devm_kzalloc(&pdev->dev, sizeof(struct serio), GFP_KERNEL);
-	if (ser_dev == NULL)
+	if (!ser_dev)
 		return -ENOMEM;
 
 	ser_dev->id.type = SERIO_PS_PSTHRU;