monitor: fix a typo

Fix usage of wrong variable, spotted by clang:
/src/qemu/monitor.c:2278:36: warning: The left operand of '&' is a garbage value
                        prot = pde & (PG_USER_MASK | PG_RW_MASK |

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/monitor.c b/monitor.c
index f258000..d291158 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2275,8 +2275,8 @@
                 end = (l1 << 39) + (l2 << 30);
                 if (pdpe & PG_PRESENT_MASK) {
                     if (pdpe & PG_PSE_MASK) {
-                        prot = pde & (PG_USER_MASK | PG_RW_MASK |
-                                      PG_PRESENT_MASK);
+                        prot = pdpe & (PG_USER_MASK | PG_RW_MASK |
+                                       PG_PRESENT_MASK);
                         mem_print(mon, &start, &last_prot, end, prot);
                     } else {
                         pd_addr = pdpe & 0x3fffffffff000ULL;