pmem: Downgrade error output to warning

There are several locations where this function is called where a memory
map isn't expected to be available and generates spurious errors.

libsel4platsupport/src/arch/x86/pmem.c

diff --git a/libsel4platsupport/src/arch/x86/pmem.c b/libsel4platsupport/src/arch/x86/pmem.c
index 2216e92..013805b 100644
--- a/libsel4platsupport/src/arch/x86/pmem.c
+++ b/libsel4platsupport/src/arch/x86/pmem.c
@@ -20,7 +20,7 @@
     seL4_X86_BootInfo_mmap_t data;
     int error = simple_get_extended_bootinfo(simple, SEL4_BOOTINFO_HEADER_X86_MBMMAP, &data, sizeof(seL4_X86_BootInfo_mmap_t));
     if (error == -1) {
-        ZF_LOGE("Could not find info");
+        ZF_LOGW("Could not find info");
         return 0;
     }
 
@@ -31,7 +31,7 @@
     seL4_X86_BootInfo_mmap_t data;
     int error = simple_get_extended_bootinfo(simple, SEL4_BOOTINFO_HEADER_X86_MBMMAP, &data, sizeof(seL4_X86_BootInfo_mmap_t));
     if (error == -1) {
-        ZF_LOGE("Could not find info");
+        ZF_LOGW("Could not find info");
         return -1;
     }
     seL4_X86_mb_mmap_t *mmap = (seL4_X86_mb_mmap_t *)((unsigned long)data.mmap);