[media] DocBook: add entry IDs for enum fe_sec_mini_cmd

enum fe_sec_mini_cmd is documented together with
FE_DISEQC_SEND_BURST.

Add xrefs for each entry there. This makes the hyperlinks at
frontend.h to go directly to the right documentation.

Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/DocBook/media/dvb/fe-diseqc-send-burst.xml

···
 	</thead>
 	<tbody valign="top">
 	<row>
-	    <entry align="char">SEC_MINI_A</entry>
+	    <entry align="char" id="SEC-MINI-A"><constant>SEC_MINI_A</constant></entry>
 	    <entry align="char">Sends a mini-DiSEqC 22kHz '0' Tone Burst to
 		select satellite-A</entry>
 	</row><row>
-	    <entry align="char">SEC_MINI_B</entry>
+	    <entry align="char" id="SEC-MINI-B"><constant>SEC_MINI_B</constant></entry>
 	    <entry align="char">Sends a mini-DiSEqC 22kHz '1' Data Burst to
 		select satellite-B</entry>
 	</row>