x86: Fix section alignment for EFI binaries

This patch fixes the section alignment specification in the linker script for
the Intel Quark X1000 SoC so that the UEFI GenFw program generates correct EFI
binaries.  See the added comment in quarkX1000.ld for details.

cpu/x86/quarkX1000.ld

@@ -52,14 +52,26 @@ SECTIONS {
     */
     . = 1M + 0x220;
 
-    .text ALIGN (32) :
+    .text : ALIGN (32)
     {
         KEEP(*(.multiboot))
         *(.boot_text)
         *(.text*)
     }
 
-    .rodata ALIGN (32) :
+    /*
+       The alignment directive must be placed after the colon so that the desired
+       alignment is indicated in the ELF section metadata.  This metadata is used
+       by the UEFI GenFw program.  It is necessary to avoid specifying a smaller
+       alignment value in the ELF metadata for some section "B" that follows some
+       section "A" with an ending address that is not aligned on a 32-byte boundary.
+       In that case, GenFw may place section "B" at a lower starting address in the
+       EFI binary than section "B" had in the input ELF file.  This may result in
+       incorrect program behavior.  Note that this situation is not directly visible
+       in the EFI binary metadata, since GenFw combines the ELF .rodata, .data, and
+       .bss sections into a single .data section in the EFI binary.
+    */
+    .rodata : ALIGN (32)
     {
         *(.rodata*)
 
@@ -72,12 +84,12 @@ SECTIONS {
         _edata_shared_isr = .;
     }
 
-    .data ALIGN (32) :
+    .data : ALIGN (32)
     {
         *(.data*)
     }
 
-    .bss ALIGN (32) :
+    .bss : ALIGN (32)
     {
         *(COMMON)
         *(.main_stack)