block: constify sect_buf argument of ide_write_data

Add a const keyword to the sect_buf argument of
ide_write_data to fix the following warning:

  cmd_ide.c: In function '__ide_output_data':
  cmd_ide.c:548: warning: passing argument 2 of 'ide_write_data' discards qualifiers from pointer target type
  /devel/u-boot.git/include/ide.h:76: note: expected 'ulong *' but argument is of type 'const ulong *'

Also modify the driver-model documentation to
match with the new prototype.

Compile tested only.

Cc: Macpaul Lin <macpaul@andestech.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

doc/driver-model/UDM-block.txt

@@ -93,7 +93,7 @@ I) Overview
       uchar ide_read_register(int dev, unsigned int port);
       void  ide_write_register(int dev, unsigned int port, unsigned char val);
       void  ide_read_data(int dev, ulong *sect_buf, int words);
-      void  ide_write_data(int dev, ulong *sect_buf, int words);
+      void  ide_write_data(int dev, const ulong *sect_buf, int words);
 
     The first two functions are called from ide_inb()/ide_outb(), and will
     default to direct memory access if CONFIG_IDE_AHB is not set, or

drivers/block/ftide020.c

@@ -81,7 +81,7 @@ void ide_write_register(int dev, unsigned int port, unsigned char val)
 		IDE_REG_DA_WRITE(port) | val);
 }
 
-void ide_write_data(int dev, ulong *sect_buf, int words)
+void ide_write_data(int dev, const ulong *sect_buf, int words)
 {
 	static struct ftide020_s *ftide020 = (struct ftide020_s *) FTIDE_BASE;
 

include/ide.h

@@ -76,7 +76,7 @@ int ide_device_present(int dev);
 unsigned char ide_read_register(int dev, unsigned int port);
 void ide_write_register(int dev, unsigned int port, unsigned char val);
 void ide_read_data(int dev, ulong *sect_buf, int words);
-void ide_write_data(int dev, ulong *sect_buf, int words);
+void ide_write_data(int dev, const ulong *sect_buf, int words);
 #endif
 
 /*