storagecommands: pass by reference

[src/storagecommands.cpp:598]:
[src/storagecommands.cpp:628]:
(performance) Function parameter 'selLogFiles' should be passed by const reference.
[src/storagecommands.cpp:642]:
(performance) Function parameter 'hexStr' should be passed by const reference.

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I0528a122f34e9b53627f041c1bdd7be4f34858ed
1 file changed