default or selected kernelversion does not have config value CONFIG_B43_PCMCIA.
Result is shown for kernelversion 4.3.6

Broadcom 43xx PCMCIA device support

configname: CONFIG_B43_PCMCIA

Linux Kernel Configuration
└─> Device Drivers
└─> Network device support
└─> Wireless LAN
└─> Broadcom 43xx PCMCIA device support

Broadcom 43xx PCMCIA device support.

Support for 16bit PCMCIA devices.
Please note that most PC-CARD devices are _NOT_ 16bit PCMCIA
devices, but 32bit CardBUS devices. CardBUS devices are supported
out of the box by b43.

With this config option you can drive b43 cards in
CompactFlash formfactor in a PCMCIA adaptor.
CF b43 cards can sometimes be found in handheld PCs.

It's safe to select Y here, even if you don't have a B43 PCMCIA device.

If unsure, say N.