typo fixes: aera -> area, exntension -> extension

One printk and one comment typo fix.

Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

arch/x86/pci/pcbios.c

@@ -44,7 +44,7 @@ static inline void set_bios_x(void)
 	pcibios_enabled = 1;
 	set_memory_x(PAGE_OFFSET + BIOS_BEGIN, (BIOS_END - BIOS_BEGIN) >> PAGE_SHIFT);
 	if (__supported_pte_mask & _PAGE_NX)
-		printk(KERN_INFO "PCI : PCI BIOS aera is rw and x. Use pci=nobios if you want it NX.\n");
+		printk(KERN_INFO "PCI : PCI BIOS area is rw and x. Use pci=nobios if you want it NX.\n");
 }
 
 /*

net/ipv4/netfilter/nf_nat_core.c

@@ -318,7 +318,7 @@ nf_nat_setup_info(struct nf_conn *ct,
 		srchash = hash_by_src(net, nf_ct_zone(ct),
 				      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
 		spin_lock_bh(&nf_nat_lock);
-		/* nf_conntrack_alter_reply might re-allocate exntension aera */
+		/* nf_conntrack_alter_reply might re-allocate extension area */
 		nat = nfct_nat(ct);
 		nat->ct = ct;
 		hlist_add_head_rcu(&nat->bysource,