misc: Doxygen tweaks: fixed some typos and minor errors

Doxygen generates quite a lot of warnings on libosmocore. Some of them
are obvious typos - this patch aims to fix such low-hanging fruit.
diff --git a/include/osmocom/core/msgb.h b/include/osmocom/core/msgb.h
index a1939ab..fe2733b 100644
--- a/include/osmocom/core/msgb.h
+++ b/include/osmocom/core/msgb.h
@@ -361,7 +361,7 @@
 }
 
 /*! \brief Trim the msgb to a given layer3 length
- *  \pram[in] msg message buffer
+ *  \param[in] msg message buffer
  *  \param[in] l3len new layer3 length
  *  \returns 0 in case of success, negative in case of error
  */