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/tam3517-common.h b/include/configs/tam3517-common.h
index 72da301..7f5a3ca 100644
--- a/include/configs/tam3517-common.h
+++ b/include/configs/tam3517-common.h
@@ -214,8 +214,8 @@
 	"addmisc=setenv bootargs ${bootargs} ${misc}\0"			\
 	"loadaddr=82000000\0"						\
 	"kernel_addr_r=82000000\0"					\
-	"hostname=" __stringify(CONFIG_HOSTNAME) "\0"			\
-	"bootfile=" __stringify(CONFIG_HOSTNAME) "/uImage\0"		\
+	"hostname=" CONFIG_HOSTNAME "\0"			\
+	"bootfile=" CONFIG_HOSTNAME "/uImage\0"		\
 	"flash_self=run ramargs addip addtty addmtd addmisc;"		\
 		"bootm ${kernel_addr} ${ramdisk_addr}\0"		\
 	"flash_nfs=run nfsargs addip addtty addmtd addmisc;"		\
@@ -230,10 +230,10 @@
 		"run ramargs addip addtty addmtd addmisc;"		\
 		"bootm ${kernel_addr_r} ${ramdisk_addr_r};"		\
 		"else echo Images not loades;fi\0"			\
-	"u-boot=" __stringify(CONFIG_HOSTNAME) "/u-boot.img\0"		\
+	"u-boot=" CONFIG_HOSTNAME "/u-boot.img\0"		\
 	"load=tftp ${loadaddr} ${u-boot}\0"				\
 	"loadmlo=tftp ${loadaddr} ${mlo}\0"				\
-	"mlo=" __stringify(CONFIG_HOSTNAME) "/MLO\0"			\
+	"mlo=" CONFIG_HOSTNAME "/MLO\0"			\
 	"uboot_addr=0x80000\0"						\
 	"update=nandecc sw;nand erase ${uboot_addr} 100000;"		\
 		"nand write ${loadaddr} ${uboot_addr} 80000\0"		\