SMS add index initialization

[pennam]

I did not test anything about SMS, but this was producing an annoying compiler warning.

[github-actions]

Memory usage change @ 624af63

Board	flash	%	RAM for global variables	%
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A
arduino:renesas_portenta:portenta_c33	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0

Click for full report table

Board	examples/HTTPClient flash	%	examples/HTTPClient RAM for global variables	%	examples/HTTPSClient flash	%	examples/HTTPSClient RAM for global variables	%	examples/GetTime flash	%	examples/GetTime RAM for global variables	%	examples/GetLocation flash	%	examples/GetLocation RAM for global variables	%	examples/DeleteSMS flash	%	examples/DeleteSMS RAM for global variables	%	examples/ReceiveSMS flash	%	examples/ReceiveSMS RAM for global variables	%	examples/SendSMS flash	%	examples/SendSMS RAM for global variables	%	examples/ModemTerminal flash	%	examples/ModemTerminal RAM for global variables	%
arduino:mbed_portenta:envie_m7	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
arduino:renesas_portenta:portenta_c33	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0

Click for full report CSV

Board,examples/HTTPClient<br>flash,%,examples/HTTPClient<br>RAM for global variables,%,examples/HTTPSClient<br>flash,%,examples/HTTPSClient<br>RAM for global variables,%,examples/GetTime<br>flash,%,examples/GetTime<br>RAM for global variables,%,examples/GetLocation<br>flash,%,examples/GetLocation<br>RAM for global variables,%,examples/DeleteSMS<br>flash,%,examples/DeleteSMS<br>RAM for global variables,%,examples/ReceiveSMS<br>flash,%,examples/ReceiveSMS<br>RAM for global variables,%,examples/SendSMS<br>flash,%,examples/SendSMS<br>RAM for global variables,%,examples/ModemTerminal<br>flash,%,examples/ModemTerminal<br>RAM for global variables,%
arduino:mbed_portenta:envie_m7,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A
arduino:renesas_portenta:portenta_c33,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0

[sebromero]

LGTM