dvbv5-tzap with pctv 290e/292e needs EAGAIN for pat/pmt to work when recording.

[Andy Furniss <adf.lists@gmail.com>]

Running kernel 3.18.14 with git master v4l-utils and a pctv290e + a 292e.

If I try to record with dvbv5-zap and include the "p" option to get
pat/pmt I get -

read_sections: read error: Resource temporarily unavailable
couldn't find pmt-pid for sid 10bf

Doing this this fixes it for me (obviously not meant to be a a proper 
patch).

diff --git a/lib/libdvbv5/dvb-demux.c b/lib/libdvbv5/dvb-demux.c
index 30d4eda..b520948 100644
--- a/lib/libdvbv5/dvb-demux.c
+++ b/lib/libdvbv5/dvb-demux.c
@@ -151,8 +151,10 @@ int dvb_get_pmt_pid(int patfd, int sid)
                 if (((count = read(patfd, buf, sizeof(buft))) < 0) && 
errno == EOVERFLOW)
                 count = read(patfd, buf, sizeof(buft));
                 if (count < 0) {
-               perror("read_sections: read error");
-               return -1;
+                       if (errno == EAGAIN) /*ADF*/
+                               continue;
+                       perror("read_sections: read error");
+                       return -1;
                 }

                 section_length = ((buf[1] & 0x0f) << 8) | buf[2];