I searched the kernel log and found these messages:
[ 1.176179] mtdoops: mtd device (mtddev=name/number) must be supplied
[ 1.184619] spi_master spi1: /ocp/spi@48030000/m25p80@0 has no 'spi-max-frequency' property
[ 1.193508] spi_master spi1: /ocp/spi@48030000/m25p80@1 has no 'spi-max-frequency' property
Following that trend I figured that I needed to add the spi-max-frequency to our tree, both nodes got the same treatment:
m25p80@0 { /* 22-24MHz */ compatible = "w25q256"; reg = <0x0>; spi-max-frequency = <23000000>; m25p,fast-read; };
And now the mtd devices show up.