objtool warnings in randconfig builds using gcc-7.1.1

[Arnd Bergmann]

Hi Josh,

With the configuration at https://pastebin.com/jHtvCwER
and gcc-7.1.1, I get these warnings

drivers/hid/wacom_wac.o: warning: objtool: wacom_bpt3_touch()+0x2a5:
stack state mismatch: cfa1=7+8 cfa2=6+16
drivers/iio/adc/vf610_adc.o: warning: objtool:
vf610_adc_calculate_rates() falls through to next function
vf610_adc_sample_set()
drivers/pwm/pwm-hibvt.o: warning: objtool: hibvt_pwm_get_state() falls
through to next function hibvt_pwm_remove()
drivers/pwm/pwm-mediatek.o: warning: objtool: mtk_pwm_config() falls
through to next function mtk_pwm_enable()
drivers/spi/spi-bcm2835.o: warning: objtool: .text: unexpected end of section
drivers/spi/spi-bcm2835aux.o: warning: objtool: .text: unexpected end of section
drivers/watchdog/digicolor_wdt.o: warning: objtool:
dc_wdt_get_timeleft() falls through to next function dc_wdt_restart()

this seems to be related to a warning I reported in older kernels that we
never fixed, but now the output is slightly different.

       Arnd