regmap: initialize dump count to 1

The count debugfs node is used to set the number of registers to read
starting at the given address. Initialize this to 1 so that data will
produce at least one entry if the count is not specified.

Change-Id: Ia0d2f5f0e145a735ab565a4530a17d83f832bb88
Signed-off-by: Nicholas Troast <ntroast@codeaurora.org>