spi/documentation: Fix usage of __initdata

__initdata should be placed between the variable name and equal
sign for the variable to be placed in the intended section. Fix
the example code.

Signed-off-by: Sachin Kamat <[e-mail]>
Acked-by: Rob Landley <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

Documentation/spi/spi-summary

···
 	/* if your mach-* infrastructure doesn't support kernels that can
 	 * run on multiple boards, pdata wouldn't benefit from "__init".
 	 */
-	static struct mysoc_spi_data __initdata pdata = { ... };
+	static struct mysoc_spi_data pdata __initdata = { ... };
 
 	static __init board_init(void)
 	{