i2c: I2C_ELEKTOR should depend on HAS_IOPORT

On m68k, I get:

drivers/i2c/busses/i2c-elektor.c: In function ‘pcf_isa_init’:
drivers/i2c/busses/i2c-elektor.c:153: error: implicit declaration of function ‘ioport_map’
drivers/i2c/busses/i2c-elektor.c:153: warning: assignment makes pointer from integer without a cast
drivers/i2c/busses/i2c-elektor.c: In function ‘elektor_probe’:
drivers/i2c/busses/i2c-elektor.c:287: error: implicit declaration of function ‘ioport_unmap’

Since commit 82ed223c ("iomap: make IOPORT/PCI
mapping functions conditional"), ioport_map() is only available on platforms
that set HAS_IOPORT.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Jean Delvare <khali@linux-fr.org>