x86: Move install_e820_map() out of zimage.c

install_e820_map() has nothing to do with zimage related codes.
Move it to a dedicated place.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
index 21bc633..351f021 100644
--- a/arch/x86/include/asm/e820.h
+++ b/arch/x86/include/asm/e820.h
@@ -23,4 +23,7 @@
 
 #endif /* __ASSEMBLY__ */
 
+/* Implementation defined function to install an e820 map */
+unsigned install_e820_map(unsigned max_entries, struct e820entry *);
+
 #endif /* _ASM_X86_E820_H */
diff --git a/arch/x86/include/asm/zimage.h b/arch/x86/include/asm/zimage.h
index bf351ed..94fa2a7 100644
--- a/arch/x86/include/asm/zimage.h
+++ b/arch/x86/include/asm/zimage.h
@@ -31,9 +31,6 @@
 #define BZIMAGE_LOAD_ADDR  0x100000
 #define ZIMAGE_LOAD_ADDR   0x10000
 
-/* Implementation defined function to install an e820 map. */
-unsigned install_e820_map(unsigned max_entries, struct e820entry *);
-
 struct boot_params *load_zimage(char *image, unsigned long kernel_size,
 				ulong *load_addressp);
 int setup_zimage(struct boot_params *setup_base, char *cmd_line, int auto_boot,