blackfin: vmlinux.lds.S: reserve 32 bytes space at the end of data section for XIP kernel

to collect some undefined section to the end of the data section and avoid section overlap
Signed-off-by: Steven Miao <realmz6@gmail.com>

arch/blackfin/kernel/vmlinux.lds.S

@@ -145,7 +145,7 @@ SECTIONS
 
 	.text_l1 L1_CODE_START : AT(LOADADDR(.exit.data) + SIZEOF(.exit.data))
 #else
-	.init.data : AT(__data_lma + __data_len)
+	.init.data : AT(__data_lma + __data_len + 32)
 	{
 		__sinitdata = .;
 		INIT_DATA