Staging: kpc2000: kpc_dma: Make some symbols static

Fix sparse warnings:

drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c:46:6: warning: symbol 'kpc_dma_del_device' was not declared. Should it be static?
drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c:84:1: warning: symbol 'dev_attr_engine_regs' was not declared. Should it be static?
drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c:91:14: warning: symbol 'kpc_dma_class' was not declared. Should it be static?
drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c:199:24: warning: symbol 'kpc_dma_plat_driver_i' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/kpc2000/kpc_dma/kpc_dma_driver.c

@@ -81,7 +81,7 @@ static ssize_t  show_engine_regs(struct device *dev, struct device_attribute *at
 		ldev->desc_completed
 	);
 }
-DEVICE_ATTR(engine_regs, 0444, show_engine_regs, NULL);
+static DEVICE_ATTR(engine_regs, 0444, show_engine_regs, NULL);
 
 static const struct attribute *ndd_attr_list[] = {
 	&dev_attr_engine_regs.attr,