octeontx2-bphy-netdev: cpri: fix compilation warnings

commit  a1a8d2587ecfa7da5cea8c5820266a73161160ec from
https://git.assembla.com/cavium/WindRiver.linux.git

Fixed following compilation warnings.

drivers/net/ethernet/marvell/octeontx2/bphy/otx2_cpri.c:60:20:
warning: no previous prototype for ‘otx2_cpri_get_netdev’
	[-Wmissing-prototypes]

drivers/net/ethernet/marvell/octeontx2/bphy/otx2_cpri.c:129:6:
warning: variable ‘sw_rd_ptr’ set but not used
	[-Wunused-but-set-variable]

Change-Id: I452b38bfd804862298db9ac06820ec59b34715da
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/51954
Tested-by: sa_ip-sw-jenkins <sa_ip-sw-jenkins@marvell.com>
Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Meng Li <Meng.Li@windriver.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>