powerpc: mpc85xx: Fix compilation with CONFIG_WDT

When CONFIG_WDT is enabled then non-DM watchdog code cannot be used due to
conflicting functions like watchdog_reset(). So disable compilation of
mpc85xx watchdog_reset() function when CONFIG_WDT is enabled.

Signed-off-by: Pali Rohár <pali@kernel.org>
diff --git a/arch/powerpc/cpu/mpc85xx/cpu.c b/arch/powerpc/cpu/mpc85xx/cpu.c
index a82516a..ba9736e 100644
--- a/arch/powerpc/cpu/mpc85xx/cpu.c
+++ b/arch/powerpc/cpu/mpc85xx/cpu.c
@@ -344,6 +344,7 @@
 }
 
 
+#ifndef CONFIG_WDT
 #if defined(CONFIG_WATCHDOG)
 #define WATCHDOG_MASK (TCR_WP(63) | TCR_WRC(3) | TCR_WIE)
 void
@@ -372,6 +373,7 @@
 		enable_interrupts();
 }
 #endif	/* CONFIG_WATCHDOG */
+#endif
 
 /*
  * Initializes on-chip MMC controllers.