net: encx24j600: fix kernel-doc syntax in file headers

The opening comment mark '/**' is used for highlighting the beginning of
kernel-doc comments.
The header for drivers/net/ethernet/microchip/encx24j600 files follows
this syntax, but the content inside does not comply with kernel-doc.

This line was probably not meant for kernel-doc parsing, but is parsed
due to the presence of kernel-doc like comment syntax(i.e, '/**'), which
causes unexpected warning from kernel-doc.
For e.g., running scripts/kernel-doc -none
drivers/net/ethernet/microchip/encx24j600_hw.h emits:
warning: expecting prototype for h(). Prototype was for _ENCX24J600_HW_H() instead

Provide a simple fix by replacing such occurrences with general comment
format, i.e. '/*', to prevent kernel-doc from parsing it.

Signed-off-by: Aditya Srivastava <yashsri421@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>