Fix a bug about stack manipulation at ACPI wakeup.

This should avoid kernel panic on kernel compiled w/o
NO_CPU_COPTFLAGS.

Suggested by:	optimized code by -mcpu=pentiumpro

sys/amd64/acpica/acpi_wakeup.c

@@ -93,6 +93,7 @@ acpi_restorecpu:			\n\
 	movl	r_esi,%esi		\n\
 	movl	r_edi,%edi		\n\
 	movl	r_esp,%esp		\n\
+	popl	%eax			\n\
 					\n\
 	pushl	r_efl			\n\
 	popfl				\n\

sys/i386/acpica/acpi_wakeup.c

@@ -93,6 +93,7 @@ acpi_restorecpu:			\n\
 	movl	r_esi,%esi		\n\
 	movl	r_edi,%edi		\n\
 	movl	r_esp,%esp		\n\
+	popl	%eax			\n\
 					\n\
 	pushl	r_efl			\n\
 	popfl				\n\