cert_create: specify command line options in the CoT

This patch introduces a new API that allows to specify command
line options in the Chain of Trust description. These command line
options may be used to specify parameters related to the CoT (i.e.
keys or certificates), instead of keeping a hardcoded list of
options in main.c.

Change-Id: I282b0b01cb9add557b26bddc238a28253ce05e44
diff --git a/tools/cert_create/src/tbbr/tbb_key.c b/tools/cert_create/src/tbbr/tbb_key.c
index 3685559..eaaf1ff 100644
--- a/tools/cert_create/src/tbbr/tbb_key.c
+++ b/tools/cert_create/src/tbbr/tbb_key.c
@@ -38,30 +38,37 @@
 static key_t tbb_keys[] = {
 	[ROT_KEY] = {
 		.id = ROT_KEY,
+		.opt = "rot-key",
 		.desc = "Root Of Trust key"
 	},
 	[TRUSTED_WORLD_KEY] = {
 		.id = TRUSTED_WORLD_KEY,
+		.opt = "trusted-world-key",
 		.desc = "Trusted World key"
 	},
 	[NON_TRUSTED_WORLD_KEY] = {
 		.id = NON_TRUSTED_WORLD_KEY,
+		.opt = "non-trusted-world-key",
 		.desc = "Non Trusted World key"
 	},
 	[BL30_KEY] = {
 		.id = BL30_KEY,
+		.opt = "bl30-key",
 		.desc = "BL30 key"
 	},
 	[BL31_KEY] = {
 		.id = BL31_KEY,
+		.opt = "bl31-key",
 		.desc = "BL31 key"
 	},
 	[BL32_KEY] = {
 		.id = BL32_KEY,
+		.opt = "bl32-key",
 		.desc = "BL32 key"
 	},
 	[BL33_KEY] = {
 		.id = BL33_KEY,
+		.opt = "bl33-key",
 		.desc = "BL33 key"
 	}
 };