Tegra: common: improve cyclomatic complexity

Code complexity is a good indication of maintainability versus
testability of a piece of software.

ISO26262 introduces the following thresholds:

    complexity < 10 is accepted
    10 <= complexity < 20 has to be justified
    complexity >= 20 cannot be accepted

Rationale is that number of test cases to fully test a piece of
software can (depending on the coverage metrics) grow exponentially
with the number of branches in the software.

This patch removes redundant conditionals from 'bl31_early_platform_setup'
handler to reduce the McCabe Cyclomatic Complexity for this function.

Change-Id: Ifb628e33269b388f9323639cd97db761a7e049c4
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>