drivers/ata/pata_ep93xx.c: use signed int type for result of platform_get_irq()

[linux-3.16-rc5/drivers/ata/pata_ep93xx.c:929]: (style) Checking if unsigned
variable 'irq' is less than zero.

Source code is

    irq = platform_get_irq(pdev, 0);
    if (irq < 0) {

but

    unsigned int irq;

$ fgrep platform_get_irq `find . -name \*.h -print`
./include/linux/platform_device.h:extern int platform_get_irq(struct
platform_device *, unsigned int);

Now using "int" type instead of "unsigned int" for "irq" variable.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=80401


Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Andrey Utkin <andrey.krieger.utkin@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>