drivers/net/ethernet: clean up mis-targeted comments

As part of the W=1 cleanups for ethernet, a million [*] driver
comments had to be cleaned up to get the W=1 compilation to
succeed. This change finally makes the drivers/net/ethernet tree
compile with W=1 set on the command line. NOTE: The kernel uses
kdoc style (see Documentation/process/kernel-doc.rst) when
documenting code, not doxygen or other styles.

After this patch the x86_64 build has no warnings from W=1, however
scripts/kernel-doc says there are 1545 more warnings in source files, that
I need to develop a script to fix in a followup patch.

The errors fixed here are all kdoc of a few classes, with a few outliers:
In file included from drivers/net/ethernet/qlogic/netxen/netxen_nic_hw.c:10:
drivers/net/ethernet/qlogic/netxen/netxen_nic.h:1193:18: warning: ‘FW_DUMP_LEVELS’ defined but not used [-Wunused-const-variable=]
 1193 | static const u32 FW_DUMP_LEVELS[] = { 0x3, 0x7, 0xf, 0x1f, 0x3f, 0x7f, 0xff };
      |                  ^~~~~~~~~~~~~~
... repeats 4 times...
drivers/net/ethernet/sun/cassini.c:2084:24: warning: suggest braces around empty body in an ‘else’ statement [-Wempty-body]
 2084 |    RX_USED_ADD(page, i);
drivers/net/ethernet/natsemi/ns83820.c: In function ‘phy_intr’:
drivers/net/ethernet/natsemi/ns83820.c:603:6: warning: variable ‘tbisr’ set but not used [-Wunused-but-set-variable]
  603 |  u32 tbisr, tanar, tanlpar;
      |      ^~~~~
drivers/net/ethernet/natsemi/ns83820.c: In function ‘ns83820_get_link_ksettings’:
drivers/net/ethernet/natsemi/ns83820.c:1207:11: warning: variable ‘tanar’ set but not used [-Wunused-but-set-variable]
 1207 |  u32 cfg, tanar, tbicr;
      |           ^~~~~
drivers/net/ethernet/packetengines/yellowfin.c:1063:18: warning: variable ‘yf_size’ set but not used [-Wunused-but-set-variable]
 1063 |   int data_size, yf_size;
      |                  ^~~~~~~

Normal kdoc fixes:
warning: Function parameter or member 'x' not described in 'y'
warning: Excess function parameter 'x' description in 'y'
warning: Cannot understand <string> on line <NNN> - I thought it was a doc line

[*] - ok it wasn't quite a million, but it felt like it.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>