arch/unicore32/kernel/clock.c: add readl() and writel() for 'PM_' macros

Add readl() and writel() for 'PM_' macros, just like another areas have
done within unicored32, or will cause compiling issue.

The related error (allmodconfig for unicored32):

    CC      arch/unicore32/kernel/clock.o
  arch/unicore32/kernel/clock.c: In function 'clk_set_rate':
  arch/unicore32/kernel/clock.c:182: warning: initialization makes integer from pointer without a cast
  arch/unicore32/kernel/clock.c:204: error: lvalue required as left operand of assignment
  arch/unicore32/kernel/clock.c:206: error: lvalue required as left operand of assignment
  arch/unicore32/kernel/clock.c:207: error: invalid operands to binary & (have 'void *' and 'long unsigned int')
  make[1]: *** [arch/unicore32/kernel/clock.o] Error 1
  make: *** [arch/unicore32/kernel] Error 2

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Acked-by: Xuetao Guan <gxt@mprc.pku.edu.cn>
Signed-off-by: Xuetao Guan <gxt@mprc.pku.edu.cn>

arch/unicore32/kernel/clock.c

@@ -179,7 +179,7 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	}
 #ifdef CONFIG_CPU_FREQ
 	if (clk == &clk_mclk_clk) {
-		u32 pll_rate, divstatus = PM_DIVSTATUS;
+		u32 pll_rate, divstatus = readl(PM_DIVSTATUS);
 		int ret, i;
 
 		/* lookup mclk_clk_table */
@@ -201,10 +201,10 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 				/ (((divstatus & 0x0000f000) >> 12) + 1);
 
 		/* set pll sys cfg reg. */
-		PM_PLLSYSCFG = pll_rate;
+		writel(pll_rate, PM_PLLSYSCFG);
 
-		PM_PMCR = PM_PMCR_CFBSYS;
-		while ((PM_PLLDFCDONE & PM_PLLDFCDONE_SYSDFC)
+		writel(PM_PMCR_CFBSYS, PM_PMCR);
+		while ((readl(PM_PLLDFCDONE) & PM_PLLDFCDONE_SYSDFC)
 				!= PM_PLLDFCDONE_SYSDFC)
 			udelay(100);
 			/* about 1ms */