treewide: Convert CONFIG_HOSTNAME to a string option

CONFIG_HOSTNAME is defined as a "plain" preprocessor string, but every
use is couched by __stringify(...).

Hence, convert it to a proper string option.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/include/configs/ea20.h b/include/configs/ea20.h
index 75353cd..ce1ed5b 100644
--- a/include/configs/ea20.h
+++ b/include/configs/ea20.h
@@ -151,7 +151,7 @@
  * to update uboot and load kernel
  */
 
-#define CONFIG_HOSTNAME ea20
+#define CONFIG_HOSTNAME "ea20"
 #define	CONFIG_EXTRA_ENV_SETTINGS				\
 	"as=3\0"							\
 	"netdev=eth0\0"						\
@@ -188,9 +188,9 @@
 	"loadaddr=c0000014\0"						\
 	"memory=32M\0"							\
 	"kernel_addr_r=c0700000\0"					\
-	"hostname=" __stringify(CONFIG_HOSTNAME) "\0"			\
-	"bootfile=" __stringify(CONFIG_HOSTNAME) "/uImage\0"		\
-	"ramdisk_file=" __stringify(CONFIG_HOSTNAME) "/image.ext2\0"	\
+	"hostname=" CONFIG_HOSTNAME "\0"			\
+	"bootfile=" CONFIG_HOSTNAME "/uImage\0"		\
+	"ramdisk_file=" CONFIG_HOSTNAME "/image.ext2\0"	\
 	"flash_self=run ramargs addip addtty addmtd addmisc addmem;"	\
 			"bootm ${kernel_addr_r}\0"			\
 	"flash_nfs=run nfsargs addip addtty addmtd addmisc addmem;"	\
@@ -219,7 +219,7 @@
 	"net_nandrw=tftp ${kernel_addr_r} ${bootfile}; run nandrwargs"	\
 		" addip addtty addmtd addmisc addmem;"			\
 		"clrlogo;bootm ${kernel_addr_r}\0"			\
-	"u-boot=" __stringify(CONFIG_HOSTNAME) "/u-boot.bin\0"		\
+	"u-boot=" CONFIG_HOSTNAME "/u-boot.bin\0"		\
 	"load_magic=if sf probe 0;then sf "				\
 		"read c0000000 0x10000 0x60000;fi\0"			\
 	"load_nand=ubi part nand0,${as};ubifsmount ubi:rootfs;"		\