hevcdsp: use a macro for .rodata section

fixes assembling on OS/2
Signed-off-by: Dave Yeo <dave.r.yeo@gmail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavcodec/x86/hevc_mc.asm

@@ -21,7 +21,7 @@
 
 %include "libavutil/x86/x86util.asm"
 
-SECTION .rodata
+SECTION_RODATA
 
 pw_1023: times 8 dw 1023