refactor(fvp): minor cleanup with TRUSTED_BOARD_BOOT

CRYPTO_SUPPORT is enabled by default when TRUSTED_BOARD_BOOT is
enabled so usage CRYPTO_SUPPORT in conjunction with TRUSTED_BOARD_BOOT
might sometime be confusing to look at.

Adding minor cleanup to make it look simpler with conditions.
No functionality changes.

Change-Id: I800524d54ea56dc27b6c6da26c75a07f5f6de984
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>

plat/arm/board/fvp/include/platform_def.h

@@ -199,10 +199,8 @@
  * PLAT_ARM_MAX_BL2_SIZE is calculated using the current BL2 debug size plus a
  * little space for growth.
  */
-#if TRUSTED_BOARD_BOOT && COT_DESC_IN_DTB
-# define PLAT_ARM_MAX_BL2_SIZE	(UL(0x1E000) - FVP_BL2_ROMLIB_OPTIMIZATION)
-#elif CRYPTO_SUPPORT
-#if TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_RSA_AND_ECDSA
+#if CRYPTO_SUPPORT
+#if (TF_MBEDTLS_KEY_ALG_ID == TF_MBEDTLS_RSA_AND_ECDSA) || COT_DESC_IN_DTB
 # define PLAT_ARM_MAX_BL2_SIZE	(UL(0x1E000) - FVP_BL2_ROMLIB_OPTIMIZATION)
 #else
 # define PLAT_ARM_MAX_BL2_SIZE	(UL(0x1D000) - FVP_BL2_ROMLIB_OPTIMIZATION)