mips: Update linker scripts to ensure appended device tree is aligned

With commit 0535e46d55 ("scripts/dtc: Update to upstream version
v1.7.2-35-g52f07dcca47c") it is now a fatal error to U-Boot if our
device tree is not 8-byte aligned. In commit 85f586035d ("ARM: OMAP2+:
Pad SPL binary to 8-byte alignment before DTB") Beleswar Padhi explains
that we must have ALIGN(x) statements inside of a section to ensure that
padding is included and not simply that the linker address counter is
incremented. To that end, this patch:
- Aligns the final section before _end (for U-Boot) or _image_binary_end
  (for xPL phases) by 8-bytes by adding '. = ALIGN(8);' to the final
  section before the symbol. For SPL we need this in two places to cover
  all build configurations.
- Remove now-spurious  '. = ALIGN(x);' statements that were intended to
  provide the above alignments.
- Ensure that we do have alignment by adding an ASSERT so that when not
  aligned we fail to link (and explain why).

Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>

arch/mips/cpu/u-boot-spl.lds

@@ -27,16 +27,17 @@ SECTIONS
 	.data : {
 		*(SORT_BY_ALIGNMENT(.data*))
 		*(SORT_BY_ALIGNMENT(.sdata*))
+		. = ALIGN(8);
 	} > .spl_mem
 
 #if defined(CONFIG_SPL_DM) || defined(CONFIG_SPL_LOADER_SUPPORT)
 	. = ALIGN(4);
 	__u_boot_list : {
 		KEEP(*(SORT(__u_boot_list*)));
+		. = ALIGN(8);
 	} > .spl_mem
 #endif
 
-	. = ALIGN(4);
 	__image_copy_end = .;
 	__image_copy_len = __image_copy_end - __text_start;
 
@@ -123,3 +124,6 @@ SECTIONS
 		*(.eh_frame)
 	}
 }
+
+ASSERT(_image_binary_end % 8 == 0, \
+       "_image_binary_end must be 8-byte aligned for device tree");

arch/mips/cpu/u-boot.lds

@@ -54,9 +54,9 @@ SECTIONS
 		LONG(0xFFFFFFFF);
 		FILL(0);
 		. += CONFIG_MIPS_RELOCATION_TABLE_SIZE - 4;
+		. = ALIGN(8);
 	}
 
-	. = ALIGN(8);
 	_end = .;
 
 	.bss __rel_start (OVERLAY) : {
@@ -140,3 +140,5 @@ SECTIONS
 		*(.eh_frame)
 	}
 }
+
+ASSERT(_end % 8 == 0, "_end must be 8-byte aligned for device tree");