Add block read support to i2cget

Use patch from https://patchwork.ozlabs.org/patch/622104/

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Resolves openbmc/openbmc#952

Change-Id: I7cda95f997be863b2fff0b6a5911d9f433b58c6c
Signed-off-by: Matt Spinler <spinler@us.ibm.com>