clk: clk-xgene: Adjust six checks for null pointers

The script “checkpatch.pl” pointed information out like the
following.

	Comparison to NULL could be written ...

Thus fix the affected source code places.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/clk-xgene.c

@@ -189,7 +189,7 @@ static void xgene_pllclk_init(struct device_node *np, enum xgene_pll_type pll_ty
 	int version = xgene_pllclk_version(np);
 
 	reg = of_iomap(np, 0);
-	if (reg == NULL) {
+	if (!reg) {
 		pr_err("Unable to map CSR register for %pOF\n", np);
 		return;
 	}
@@ -465,7 +465,7 @@ static int xgene_clk_enable(struct clk_hw *hw)
 	if (pclk->lock)
 		spin_lock_irqsave(pclk->lock, flags);
 
-	if (pclk->param.csr_reg != NULL) {
+	if (pclk->param.csr_reg) {
 		pr_debug("%s clock enabled\n", clk_hw_get_name(hw));
 		/* First enable the clock */
 		data = xgene_clk_read(pclk->param.csr_reg +
@@ -505,7 +505,7 @@ static void xgene_clk_disable(struct clk_hw *hw)
 	if (pclk->lock)
 		spin_lock_irqsave(pclk->lock, flags);
 
-	if (pclk->param.csr_reg != NULL) {
+	if (pclk->param.csr_reg) {
 		pr_debug("%s clock disabled\n", clk_hw_get_name(hw));
 		/* First put the CSR in reset */
 		data = xgene_clk_read(pclk->param.csr_reg +
@@ -531,7 +531,7 @@ static int xgene_clk_is_enabled(struct clk_hw *hw)
 	struct xgene_clk *pclk = to_xgene_clk(hw);
 	u32 data = 0;
 
-	if (pclk->param.csr_reg != NULL) {
+	if (pclk->param.csr_reg) {
 		pr_debug("%s clock checking\n", clk_hw_get_name(hw));
 		data = xgene_clk_read(pclk->param.csr_reg +
 					pclk->param.reg_clk_offset);
@@ -540,7 +540,7 @@ static int xgene_clk_is_enabled(struct clk_hw *hw)
 							"disabled");
 	}
 
-	if (pclk->param.csr_reg == NULL)
+	if (!pclk->param.csr_reg)
 		return 1;
 	return data & pclk->param.reg_clk_mask ? 1 : 0;
 }
@@ -705,7 +705,7 @@ static void __init xgene_devclk_init(struct device_node *np)
 			break;
 		}
 		map_res = of_iomap(np, i);
-		if (map_res == NULL) {
+		if (!map_res) {
 			pr_err("Unable to map resource %d for %pOF\n", i, np);
 			goto err;
 		}