spl: nand: read only in the size of image_header on the first access

For the same reason as in commit 50c8d66d, all the remaining
CONFIG_SYS_NAND_PAGE_SIZE in common/spl/spl_nand.c can be replaced
with sizeof(*header).

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Tim Harvey <tharvey@gateworks.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>

common/spl/spl_nand.c

@@ -44,7 +44,7 @@ void spl_nand_load_image(void)
 
 		/* load linux */
 		nand_spl_load_image(CONFIG_SYS_NAND_SPL_KERNEL_OFFS,
-			CONFIG_SYS_NAND_PAGE_SIZE, (void *)header);
+			sizeof(*header), (void *)header);
 		spl_parse_image_header(header);
 		if (header->ih_os == IH_OS_LINUX) {
 			/* happy - was a linux */
@@ -62,13 +62,13 @@ void spl_nand_load_image(void)
 #endif
 #ifdef CONFIG_NAND_ENV_DST
 	nand_spl_load_image(CONFIG_ENV_OFFSET,
-		CONFIG_SYS_NAND_PAGE_SIZE, (void *)header);
+		sizeof(*header), (void *)header);
 	spl_parse_image_header(header);
 	nand_spl_load_image(CONFIG_ENV_OFFSET, spl_image.size,
 		(void *)spl_image.load_addr);
 #ifdef CONFIG_ENV_OFFSET_REDUND
 	nand_spl_load_image(CONFIG_ENV_OFFSET_REDUND,
-		CONFIG_SYS_NAND_PAGE_SIZE, (void *)header);
+		sizeof(*header), (void *)header);
 	spl_parse_image_header(header);
 	nand_spl_load_image(CONFIG_ENV_OFFSET_REDUND, spl_image.size,
 		(void *)spl_image.load_addr);