fix(fconf): fix FCONF_ARM_IO_UUID_NUMBER value

fix(fconf): fix FCONF_ARM_IO_UUID_NUMBER value

The FCONF_ARM_IO_UUID_NUMBER macro is hardcoded to the number of entries
in the `load_info` array, but this number did not match the actual
length of the array in the case that TRUSTED_BOARD_BOOT is defined, but
SPD_spmd is not defined.

This patch fixes the hardcoded length by replacing it with a more
flexible calculation which sums up the various contributing groups of
entries.

Signed-off-by: Rob Hughes <robert.hughes@arm.com>
Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>
Change-Id: I557bca7dd32c3be084bbba11d84dfa2818cb6790