Update pk2ldr outline, prepare for bootup_misc_mmio() impl

exosphere/src/bootup.c

@@ -0,0 +1,18 @@
+#include <stdint.h>
+
+#include "utils.h"
+#include "bootup.h"
+
+void bootup_misc_mmio(void) {
+    /* TODO */
+    /* This func will also be called on warmboot. */
+    /* And will verify stored SE Test Vector, clear keyslots, */
+    /* Generate an SRK, set the warmboot firmware location, */
+    /* Configure the GPU uCode carveout, configure the Kernel default carveouts, */
+    /* Initialize the PMC secure scratch registers, initialize MISC registers, */
+    /* And assign "se_operation_completed" to Interrupt 0x5A. */
+}
+
+void setup_4x_mmio(void) {
+    /* TODO */
+}