ppc/85xx: Use CONFIG_NS16550_MIN_FUNCTIONS to reduce NAND_SPL size

The MPC8536DS_NAND SPL build was failing due to code size increase
introduced by commit:

commit 33f57bd553
Author: Kumar Gala <galak@kernel.crashing.org>
Date:   Fri Mar 26 15:14:43 2010 -0500

    85xx: Fix enabling of L1 cache parity on secondary cores

We built in some NS16550 functions that we dont need and can get
rid of them via CONFIG_NS16550_MIN_FUNCTIONS.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

include/configs/MPC8536DS.h

@@ -413,6 +413,9 @@ extern unsigned long get_board_ddr_clk(unsigned long dummy);
 #define CONFIG_SYS_NS16550_SERIAL
 #define CONFIG_SYS_NS16550_REG_SIZE	1
 #define CONFIG_SYS_NS16550_CLK		get_bus_freq(0)
+#ifdef CONFIG_NAND_SPL
+#define CONFIG_NS16550_MIN_FUNCTIONS
+#endif
 
 #define CONFIG_SYS_BAUDRATE_TABLE	\
 	{300, 600, 1200, 2400, 4800, 9600, 19200, 38400,115200}

include/configs/MPC8569MDS.h

@@ -284,6 +284,9 @@ extern unsigned long get_clock_freq(void);
 #define CONFIG_SYS_NS16550_SERIAL
 #define CONFIG_SYS_NS16550_REG_SIZE    1
 #define CONFIG_SYS_NS16550_CLK		get_bus_freq(0)
+#ifdef CONFIG_NAND_SPL
+#define CONFIG_NS16550_MIN_FUNCTIONS
+#endif
 
 #define CONFIG_SYS_BAUDRATE_TABLE  \
 	{300, 600, 1200, 2400, 4800, 9600, 19200, 38400,115200}

include/configs/P1_P2_RDB.h

@@ -286,6 +286,9 @@ extern unsigned long get_board_sys_clk(unsigned long dummy);
 #define CONFIG_SYS_NS16550_SERIAL
 #define CONFIG_SYS_NS16550_REG_SIZE	1
 #define CONFIG_SYS_NS16550_CLK		get_bus_freq(0)
+#ifdef CONFIG_NAND_SPL
+#define CONFIG_NS16550_MIN_FUNCTIONS
+#endif
 
 #define CONFIG_SERIAL_MULTI	1 /* Enable both serial ports */
 #define CONFIG_SYS_CONSOLE_IS_IN_ENV	/* determine from environment */