net: usb: lan78xx: Remove lots of set but unused 'ret' variables

Fixes the following W=1 kernel build warning(s):

 drivers/net/usb/lan78xx.c: In function ‘lan78xx_read_raw_otp’:
 drivers/net/usb/lan78xx.c:825:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_write_raw_otp’:
 drivers/net/usb/lan78xx.c:879:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_deferred_multicast_write’:
 drivers/net/usb/lan78xx.c:1041:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_update_flowcontrol’:
 drivers/net/usb/lan78xx.c:1127:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_init_mac_address’:
 drivers/net/usb/lan78xx.c:1666:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_link_status_change’:
 drivers/net/usb/lan78xx.c:1841:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_irq_bus_sync_unlock’:
 drivers/net/usb/lan78xx.c:1920:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan8835_fixup’:
 drivers/net/usb/lan78xx.c:1994:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_set_rx_max_frame_length’:
 drivers/net/usb/lan78xx.c:2192:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_change_mtu’:
 drivers/net/usb/lan78xx.c:2270:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_set_mac_addr’:
 drivers/net/usb/lan78xx.c:2299:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_set_features’:
 drivers/net/usb/lan78xx.c:2333:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
 drivers/net/usb/lan78xx.c: In function ‘lan78xx_set_suspend’:
 drivers/net/usb/lan78xx.c:3807:6: warning: variable ‘ret’ set but not used [-Wunused-but-set-variable]
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201102114512.1062724-25-lee.jones@linaro.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>