rtlwifi: rtl8192c: Remove set but not used variables 'reg_ecc','reg_eac'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/wireless/realtek/rtlwifi/rtl8192c/phy_common.c: In function rtl92c_phy_iq_calibrate:
drivers/net/wireless/realtek/rtlwifi/rtl8192c/phy_common.c:1373:6: warning: variable reg_ecc set but not used [-Wunused-but-set-variable]
drivers/net/wireless/realtek/rtlwifi/rtl8192c/phy_common.c: In function rtl92c_phy_iq_calibrate:
drivers/net/wireless/realtek/rtlwifi/rtl8192c/phy_common.c:1372:34: warning: variable reg_eac set but not used [-Wunused-but-set-variable]

They are not used since commit f1d2b4d3 ("rtlwifi:
rtl818x: Move drivers into new realtek directory")

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>