x86: rename KERNEL_TEXT_SIZE => KERNEL_IMAGE_SIZE

The KERNEL_TEXT_SIZE constant was mis-named, as we not only map the kernel
text but data, bss and init sections as well.

That name led me on the wrong path with the KERNEL_TEXT_SIZE regression,
because i knew how big of _text_ my images have and i knew about the 40 MB
"text" limit so i wrongly thought to be on the safe side of the 40 MB limit
with my 29 MB of text, while the total image size was slightly above 40 MB.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/head_64.S

@@ -393,7 +393,7 @@ NEXT_PAGE(level2_kernel_pgt)
 	 *  too.)
 	 */
 	PMDS(0, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL,
-		KERNEL_TEXT_SIZE/PMD_SIZE)
+		KERNEL_IMAGE_SIZE/PMD_SIZE)
 
 NEXT_PAGE(level2_spare_pgt)
 	.fill   512, 8, 0

include/asm-x86/page_64.h

@@ -51,8 +51,8 @@
  * Kernel image size is limited to 128 MB (see level2_kernel_pgt in
  * arch/x86/kernel/head_64.S), and it is mapped here:
  */
-#define KERNEL_TEXT_SIZE	(128*1024*1024)
-#define KERNEL_TEXT_START	_AC(0xffffffff80000000, UL)
+#define KERNEL_IMAGE_SIZE	(128*1024*1024)
+#define KERNEL_IMAGE_START	_AC(0xffffffff80000000, UL)
 
 #ifndef __ASSEMBLY__
 void clear_page(void *page);