uio: pruss: fix to check return value of platform_get_irq() in pruss_probe()

The platform_get_irq might be failed and return a negative result. So
there should have an error handling code.

Fixed this by adding an error handling code.

Signed-off-by: Zhang Shurong <zhang_shurong@foxmail.com>
Link: https://lore.kernel.org/r/tencent_8E383752B54E5BF860711E500AD8A8971208@qq.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>