Fix warnings reported by UBSAN

fixed the following warnings reported by UBSAN:

1) modules/crypto/tinycrypt/lib/source/aes_encrypt.c:93:8:
runtime error: left shift of 251 by 24 places
cannot be represented in type 'int'

2)modules/crypto/tinycrypt/lib/source/aes_encrypt.c:86:25:
runtime error: left shift of 250 by 24 places
cannot be represented in type 'int'

Signed-off-by: Ivan Iushkov <ivan.iushkov@nordicsemi.no>

lib/source/aes_encrypt.c

@@ -64,7 +64,7 @@ static inline unsigned int rotword(unsigned int a)
 	return (((a) >> 24)|((a) << 8));
 }
 
-#define subbyte(a, o)(sbox[((a) >> (o))&0xff] << (o))
+#define subbyte(a, o)((uint32_t)sbox[((a) >> (o))&0xff] << (o))
 #define subword(a)(subbyte(a, 24)|subbyte(a, 16)|subbyte(a, 8)|subbyte(a, 0))
 
 int tc_aes128_set_encrypt_key(TCAesKeySched_t s, const uint8_t *k)
@@ -83,7 +83,7 @@ int tc_aes128_set_encrypt_key(TCAesKeySched_t s, const uint8_t *k)
 	}
 
 	for (i = 0; i < Nk; ++i) {
-		s->words[i] = (k[Nb*i]<<24) | (k[Nb*i+1]<<16) |
+		s->words[i] = ((uint32_t)k[Nb*i]<<24) | (k[Nb*i+1]<<16) |
 			      (k[Nb*i+2]<<8) | (k[Nb*i+3]);
 	}