ARM: assembler.h: Add string declaration macro

Declaring strings in assembler source involves a certain amount of
tedious boilerplate code in order to annotate the resulting symbol
correctly.

Encapsulating this boilerplate in a macro should help to avoid some
duplication and the occasional mistake.

Signed-off-by: Dave Martin <[e-mail]>
Acked-by: Nicolas Pitre <[e-mail]>

arch/arm/include/asm/assembler.h

···
 	.macro	ldrusr, reg, ptr, inc, cond=al, rept=1, abort=9001f
 	usracc	ldr, \reg, \ptr, \inc, \cond, \rept, \abort
 	.endm
+
+/* Utility macro for declaring string literals */
+	.macro	string name:req, string
+	.type \name , #object
+\name:
+	.asciz "\string"
+	.size \name , . - \name
+	.endm
+
 #endif /* __ASM_ASSEMBLER_H__ */